Bones found on the Crestavilla senior living community site are thought to be millions of years old.

The senior living community of Crestavilla will be opening later this year in Laguna Niguel, CA, having displaced some long-time residents that will be moving to the Natural History Museum of Los Angeles County.

During excavation of the property in 2016, builders found various fossils on the site, including prehistoric whales, sharks and a six-foot-long tuna that is the only complete, large tuna fossil skeleton ever found in North America and is thought to be a newly identified species between 2 million and 5 million years old.

The community is being built in an area with a geologic formation known to contain fossils, and builders were prepared for a potential find.

“Part of the process of building in the state of California is to have a monitor, and that monitor is there to watch for fossils, any archeological finds, anything of historical significance for the state of California,” said Bob Farina, senior superintendent of the project for Bernards Builders. The discovery still was “pretty amazing,” he added.

The bones may be gone, but they will not be forgotten: Crestavilla said that a replica of the tuna skeleton will be created and have a permanent home there, along with other prehistoric whale bones and shark teeth fossils.

“We are so pleased the fossils will be on display and that we had the opportunity to donate them to such an incredible museum who will preserve them for everyone to see and enjoy for many years,” said Chris Anderson, the executive director of Crestavilla, which is owned by Steadfast Companies and managed by Integral Senior Living.

The independent living, assisted living and memory care community will offer 201 units — studio, one- and two-bedroom apartments — when complete.