SOFTSHELL

Etymology

Adjective

softshell (not comparable)

(zoology) Having a relatively soft shell.

Noun

softshell (plural softshells)

A softshell turtle (Trionychidae).

Source: Wiktionary

Soft"-shell`, Soft"-shelled`, a.

Definition: Having a soft or fragile shell. Soft-shell clam (Zoöl.), the long clam. See Mya.

– Soft-shelled crab. (Zoöl.) See the Note under Crab, 1.

– Soft-shelled turtle. (Zoöl.) Same as Soft tortoise, under Soft.

Source: Webster’s Unabridged Dictionary 1913 Edition