A Crivit, burrowing in the sand.
Crivits are dangerous extraterrestrial carnivores, presumably from the Visitor's homeworld (though possibly some other planet) that live under the sand and consume any creature that walks upon the mote's surface.
A Crivit devouring a man, trying to escape a Visitor prison.
At a Visitor prison camp where Mike Donovan, Ham Tyler, Kyle Bates, and Robin Maxwell were held, a sand malt surrounded the camp and a crivit devoured a man trying to escape.
Diana has a crivit aboard her ship and she fed Kenneth, a Visitor, to it.