Vermetus \Ver*me"tus\, n. [NL., from L. vermis worm.] (Zo["o]l.) Any one of many species of marine gastropods belonging to {Vermetus} and allied genera, of the family {Vermetid[ae]}. Their shells are regularly spiral when young, but later in life the whorls become separate, and the shell is often irregularly bent and contorted like a worm tube.