Do sea otters use rocks as tools?

The Claim

Sea otters use rocks to open hard-shelled prey.

The Answer

Government and aquarium education sources describe sea otters using rocks as anvils or hammers to access food such as shellfish.

Why This Is Surprising

It sounds like the kind of claim that races around social feeds without context. The source trail matters because the best version of the wonder is the verified one.

How We Checked It

We looked for an authoritative primary source, checked the wording against at least one credible secondary source when available, and recorded the last review date.