This is a carapace from a small crab. A carapace is part of a crab's exoskeleton. This carapace was left by a crab after it molted. We think it was from a Dungeness crab. As they grow, crabs need bigger shells. They can molt up to 15 times in their life, and get carapaces that are as big as 10 inches (25 cm) across! A Dungeness crab can live to be 8 to 13 years old.
Clue #1 This thing came from a living creature.
Clue #2 It liked to hang out on the sea floor.
Clue #3 It liked to eat clams, crustaceans and small fish.