A white bison calf, born in Yellowstone National Park at the start of June, has not been seen since, according to park officials.

There haven’t been any confirmed sightings of the calf since June 4, when several visitors first took photographs of the newborn in the Lamar Valley area of the park.

Park staff said they hadn’t been able to locate the calf, and it’s unclear if the calf is still alive.

White bison — especially ones that aren’t a result of albinism — are extremely rare, and it is said that just 1 in 10 million exist.

Many Native American tribes consider white buffalo to be sacred. Leaders recently held a special ceremony near the park to honor the white calf, believing it has fulfilled a tribal prophecy.

The prophecy means people need to take better care of Mother Earth and must come together to do so, Native American leaders said during the sacred ceremony near Hebgen Lake in Montana.

They named the calf Wakan Gli, which means “Return Sacred” in Lakota.

Representatives from the Shoshone-Bannock, Lakota, Sioux, Northern Arapaho and Colville tribes were present at the ceremony, according to local news outlets.