What is this hinged tool with a box full of wicked grooves and teeth?
This is an ice crusher.

You put some cubes (or use your ice pick to cut a hunk off from a large block), put it in the compartment, and squeeze it closed. Those gnarly bumps and teeth will crush the ice.
I would personally consider it more &quot;home bar equipment&quot; for crushing ice for cocktails, though that's certainly not the only use. As mentioned in the comments, it probably doubles as a decent nutcracker, though that's not it's intended purpose.