(KRON) — A dead dolphin washed ashore at Rockaway Beach in Pacifica Sunday, the Marine Mammal Center confirmed. Officials said it was a Risso’s dolphin, also known as a gray dolphin.

The Marine Mammal Center said when crews responded to the reports to pick up the dolphin’s carcass on Monday, it had washed back out to sea. Officials said they have not heard reports of the dolphin since.

Details of the dolphin including the cause of death remain unclear.

“Although not rare, it’s not as common to see Risso’s dolphins wash ashore along the central and northern California coast compared to common dolphins, bottlenose dolphins and harbor porpoises,” Marine Mammal Center officials said.

Officials said the Center has responded to other Risso’s dolphins washing ashore in the Bay Area before, including one in September 2021 at the same beach in Pacifica. Risso’s dolphins are not considered endangered or threatened in the U.S., according to the National Oceanic and Atmospheric Association.

This comes after a dead gray whale washed ashore at a beach in Marin County—the third whale to wash up in the Bay Area so far this year—during what Cal Academy officials are calling an “Unusual Mortality Event” for the species. This was one of two dead gray whales spotted in Point Reyes National Seashore over the weekend, officials with the Marine Mammal Center told KRON4.