scleroderm

from The Century Dictionary.

• noun The hard or stony external skeleton of sclerodermatous zoantharians, or corals in an ordinary sense; corallum; coral.
• noun A member of the Sclerodermata, as a madrepore.
• noun A plectognath fish of the group Sclerodermi, having the skin rough and hard, as the file-fish, etc.
• Of or pertaining to the Sclerodermi; sclerodermous.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Zoöl.) One of a tribe of plectognath fishes (Sclerodermi) having the skin covered with hard scales, or plates, as the cowfish and the trunkfish.
• noun One of the Sclerodermata.
• noun Hardened, or bony, integument of various animals.