Editing Seashell (section)

=== Arthropods ===
[[File:Crab from Long Island.jpg|thumb|The moulted [[carapace]] of a [[lady crab]] found on the beach at [[Long Beach, New York|Long Beach, Long Island, New York State]]]]
[[File:Horseshoe Crab remains.jpg|thumb|left|Shell of [[horseshoe crab]] on a beach]]

Many [[arthropod]]s have [[sclerite]]s, or hardened body parts, which form a stiff exoskeleton made up mostly of [[chitin]].  In [[crustacean]]s, especially those of the class [[Malacostraca]] (crabs, shrimps and lobsters, for instance), the plates of the exoskeleton may be fused to form a more or less rigid [[carapace]]. Moulted carapaces of a variety of marine malacostraceans often wash up on beaches. The [[horseshoe crab]] is an arthropod of the family [[Limulidae]]. The shells or [[exuviae]] of these arachnid relatives are common in beach drift in certain areas of the world.