What rudimentary tool use is documented when macaques secure hard-shelled prey?

Answer

Using stones as hammers or anvils

In documented cases, these monkeys manipulate their environment by utilizing stones as hammers or anvils to break open tough shells of prey like crabs, demonstrating basic tool use.

What rudimentary tool use is documented when macaques secure hard-shelled prey?
dietanimalCrabPrimateMacaque