KALAELOA, Hawaii -- A 6-acre parcel near Kalaeloa will never be developed, thanks to a developer.

Over the past four years, the site has been an anthropologist's dream. Now, the developer plans to protect it.

Right at the border of Campbell Industrial Park is a fenced-in area. It comprises of 6 acres that, 120,000 years ago, was a coral reef, scientists said.

Once the water receded, sinkholes were left. In the holes, bones were found in the 1970s.

"They realized this was something they don't know about. I think people started, archaeologists started coming out and getting permission from Campbell Estate to excavate these sinkholes to see what was here," said Marjorie Ziegler of Conservation Council for Hawaii.

People found the bones of several extinct native Hawaiian birds. Zeigler's father, zoologist Alan Ziegler, found many of the bones.

"'We found something significant on your property,'" Kapolei Property Development's David Rae said. "Those are not the words a developer wants to hear."

Ziegler was able to convince the developer to preserve the area. Kapolei Property Development fenced it in. The company is in talks with the state to put the location into some state control.

The developer named the new preserve after Ziegler, who died five years ago.

More holes are still being discovered. One was found when a kiawe tree was uprooted to clear the area for a dedication ceremony.

"We don't know (how many sinkholes exist) because, as you can see, it's all covered by kiawe scrub, and a lot of times the plants start in those holes. So, as they grow bigger, they kind of destroy the holes," Ziegler said.

Conservationists hope future generations will be able to explore the sinkholes and make even more finds.