cockleshell

noun

Etymology: From cockle + shell.

1. The shell of a cockle (or similar shell).

   “The moment land had disappeared, the great canoe seemed no larger than a cockleshell; the waves lapped dangerously near to the tops of the gunwales, all but toppling into the canoe; and that is the curious thing about Polynesian canoes: the water always laps just to the tops of the gunwales, no matter whether the canoe is shallow or deep, whether empty or heavily laden.”

2. A small, flimsy boat.