This is a molted carapace (shell) of a Horseshoe Crab (Limulus polyphemus). This species is native to the Atlantic Coast and Gulf of Mexico in USA waters. This shell is from a large individual and measures approx. 10 inches long x 6 inches wide. It is in good condition and has been lightly cleaned. It could use a more thorough cleaning to remove mineralized sand which is still present in some of the nooks and crannies, or it can be displayed as-is.
Refer to the photos. The black centimeter cube is shown for scale and is not included. You are purchasing the specimen shown. Your purchase will include an ID label.