Difficulty: Summiteer (Level 3)

The base of a skull belonging to a marine giant washed ashore along Pajaro Dunes State Beach in the US state of California. Many curious locals took photos.

Experts believe it might be the lower part of the skull – called the basicranium – of either a fin whale or blue whale. Both of these whales are endangered marine species.

In the past, whale remains have washed up in other parts of California. In 2022, low tides revealed a trove of fossils.

Like all whale species, fin whales were aggressively hunted by commercial whalers in the 20th century. By the mid-1900s, more than 700,000 of them were killed.

The practice was mostly outlawed by the 1980s. But ship strikes, climate change and entanglement continue to pose a threat to the population today. Similarly, the blue whale population is just a fraction of what it once was.