having diamond-shaped markings on the back
- a large, poisonous rattlesnake (Crotalus adamanteus) with diamond-shaped markings on its back, native to the S U.S.
- an edible turtle (Malaclemys terrapin) with diamond-shaped markings on its shell, found in coastal salt marshes from Cape Cod to Mexicoin full diamondback terrapin
- a small, brown-and-white cosmopolitan moth (Plutella xylostella) whose wings, when folded, form a diamond
- A common name used of two species of rattlesnake having a diamond pattern on its back, i.e. Crotalus adamanteus found in the southeastern United States and Crotalus atrox found in southwestern United States and northwestern and central Mexico.
- The saltmarsh terrapin of the Atlantic coast (Malacoclemmys palustris).