Long before Kauai’s southeastern shore became a magnet for golf courses, hotels and luxury condominiums, molten lava flowing over roughly 6,000 acres built a vast underground world of caves and caverns.

These subterranean voids, only a small number of which are accessible, are the only known habitat for two native endangered species — the Kauai cave wolf spider, which has three teeth to eat its prey and no eyes, and the Kauai cave amphipod, a blind, shrimp-like crustacean about the size of a fingernail.

Discovered in the early 1970s, these tiny cave-dwellers are known to exist in a handful of caves in the Koloa basin area and nowhere else on earth. Federal wildlife regulators say it’s reasonable to think the invertebrates also reside in other nearby lava tubes unexplored by scientists due to their inaccessibility.

Last week, explosions used to break rock as part of a land-grading project for a planned 279-unit luxury condo complex exposed a hole in the earth that some environmentalists say appears to be a preexisting underground cavern that could be critical habitat for the pair of endangered species.

The environmental group Save Koloa, which says it’s guarding the potential last refuge of the town’s imperiled sightless creatures, has since broadcast drone footage of the new opening in the earth, generating outrage online among a broad cross-section of Kauai residents who want the blasting to stop.

The developer says it’s all a misunderstanding.

There’s no evidence of the imperiled creatures beneath the planned Kauanoe O Koloa condo complex, partly because the subterranean environment cannot be probed. But the 25-acre parcel where the blasting has occurred is adjacent to a series of explored underground passageways where the Koloa cave wolf spider has been known to dwell off of Kiahuna Golf Club‘s second fairway.

A principal threat to both blind species is habitat loss in part due to “grading, paving, quarrying and other activities associated with development,” according to the U.S. Fish and Wildlife Service.

On Wednesday, about 80 people waving Hawaiian flags and signs gathered at the condo construction site to protest the excavation work, which is expected to continue for eight months with three to four blasts occurring weekly, according to a courtesy notice provided to neighbors.

Those who oppose the blasting include environmentalists worried about the looming extinction of rare native species, as well as Hawaiian activists who say the bones of their ancestors are buried in the vicinity of the condo development. Others dispute the construction of yet another luxury vacation homes complex at a time when local people are being displaced by the scarcity of lower- and middle-class housing.

“There’s no more Hawaiians in Koloa,” said 29-year-old Elizabeth Okinaka, an organizer with Save Koloa. “Who can afford to live here with all these multimillion dollar homes?”

Hawaiian activist Keoni DeFranco, 34, said he took time away from work on Oahu to fly to Kauai for the demonstration because he wants the 25-acre construction site preserved for its unique underground geology.

“For people like me who feel strongly about my cultural identity, it’s one thing to see a video posted online. It’s another thing to witness it,” DeFranco said. “Once you see it in person you cannot deny what is occurring here, which is gentrification at an extreme level and the literal collapse of our rich cultural and archeological heritage. It should be hands-off forever.”

Citing harm to endangered wildlife habitat, a lawsuit filed last month in 5th Circuit Court by Save Koloa claims the developer is jeopardizing Hawaii residents’ environmental interests under a section of the state constitution, which declares that each person has the right to natural resource conservation and protection. Kauai County, which approved the developer’s grading and grubbing permit, is also named a defendant.

Colin Thompson, vice president of construction at Pacific Meridian, which is developing the condo project, said protesters have misinterpreted footage of crevices in the earth that have been widely shared on social media.

Excavation crews are using “micro-blasting” methods to build infrastructure improvements, such as storm water drainage, with a degree of precision that will not damage cave systems on neighboring parcels, according to Thompson. The project has a team of expert geologists, biologists and archaeologists who conducted pre-drilling tests, site surveys and ongoing monitoring to ensure that the blasting will not have adverse environmental effects.

Chuck Blay, a geologist hired by the developer to monitor the blasting, said in the same press release that voids in the ground created by excavation work are not caves or caverns, but “large, angular blocks of blue rock being broken up by the micro-blasting methods.”

Biologist Steven Lee Montgomery, who is also retained by the developer, confirmed that the blasting has not unearthed any preexisting caves or caverns, adding that he sees “no evidence for the claims made by those who released the images and videos,” according to the press release.

The clash between development and imperiled species at the Kauanoe O Koloa site dates to the 1970s, when the state Land Use Commission reclassified more than 450 acres of Koloa agricultural land for urban use in response to a request from a developer who proposed to build affordable houses and apartments.

This land use change more than 40 years ago enabled the Kauanoe O Koloa subdivision under development today.

Last month, an archaeological study funded by the developer — a state-ordered prerequisite to construction — found no evidence and “very low probability” of the presence of the endangered spider or amphipod on or in the vicinity of the parcel, in part due to the absence of underground moisture. The species can only survive where there is enough humidity to sustain a food source.

The report concludes that there is no spider or amphipod habitat on the parcel “deemed worthy of preservation,” while noting the limitations of the “sparse data” from which to draw an objective answer.

In his report, Oahu-based biologist Steven Lee Montgomery, whose half-century career in Hawaii includes field work in Koloa cave systems, wrote it’s “reassuring to note” that a scientist will be present during construction to monitor for any “moist, food containing voids” that might be inhabited by the spider or amphipod.

Although not legally binding, the FWS last year recommended to Kauai County officials that, “if a cave is found during construction, work around the cave stops immediately.” Federal and state environmental regulators should also be contacted to provide guidance on how to minimize and mitigate adverse effects to the endangered species, the agency said.

Local activists dispute claims that holes exposed by blasting were not preexisting and say the developer has not adhered to the FWS guidance.

“Tragically, I don’t know what impact all of the grading and explosions have had on the endangered species or if it’s already too late,” said Peter Morimoto, the Kauai-based attorney representing Save Koloa in the lawsuit.

Adam Asquith, a former FWS biologist, spent years crawling around Koloa’s cave systems in the 1990s to research the rare spider and amphipod, eventually writing the biological justification that led the agency to designate them as endangered species.

He said it would be “most unusual” if the Kauanoe parcel did not contain suitable habitat for the spider and amphipod since there’s known habitat on the golf course approximately 200 yards away from the property line.

But for Asquith, the question of whether the developer must legally pause construction to mitigate harm to any species that may — or may not — be present on the property is besides the point. He faults the developer for a lack of effort toward the goal of figuring out what really lies beneath its real estate investment before moving forward with potentially detrimental site grading.

“When you chant E Ho Mai, you’re asking to be shown the hidden nature of what we can’t see,” said Asquith, referencing the chant composed by late kumu hula Edith Kanakaole. “Everybody from kindergarteners to kupuna, in state meetings and in federal meetings, we all chant E Ho Mai because we can’t see all the important things. In fact, most important things in life have to be revealed to us, so we ask for guidance.”

“I think that’s the fundamental problem,” Asquith continued. “They’re not asking, ‘Please show me what might be there so that we can make the right decisions.’ And that’s not consistent with our values in Hawaii.”