I’ve had many people come up to me and ask why are there so many dead horseshoe crabs on the beaches and what is killing them.
Finding horseshoe crab shells in shallow water
What they are looking at are not dead horseshoe crabs but their molts that they need to shed at least once a year. In areas where Limulus is common, the shells, exoskeletons or exuviae (molted shells) of horseshoe crabs frequently wash up on beaches, either as whole shells, or as disarticulated pieces.
The shell of these animals consists of three parts.