zebra mussel

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A small freshwater mussel (Dreissena polymorpha) usually having a striped shell, native to the Black and Caspian Seas but now widespread in European and North American lakes and rivers.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A striped mussel, Dreissena polymorpha, originating in Russia.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun inch long mollusk imported accidentally from Europe; clogs utility inlet pipes and feeds on edible freshwater mussels