This is the dominant "crusher" claw from a lobster (family *Nephropidae* or *Homeridae*). This claw is full of slow-twitch muscles and used for a powerful, sustained grip. The opposite claw (not shown) is the "pincer claw" which is full of fast-twitch muscles and used for rapid, seizing motions.
More interesting lobster facts here: http://www.lobsters.org/ldoc/ldocpage.php?did=443
Serial number: 43.17
Captured with Artec Spider 3D Scanner https://www.artec3d.com/portable-3d-scanners/artec-spider-v2