Shifty Looking Cow

From Mass Effect Wiki

The Shifty Looking Cow is a Space Cow found on the planet Ontarom, in the Newton system of the Kepler Verge. An otherwise normal member of the species, the Shifty Looking Cow likewise has a dialog option that does nothing. When Shepard turns around, however, the Cow promptly begins stealing Shepard's credits, and will even follow the commander around. It can be found near the southwestern corner of the map--appropriately enough, near a deposit of gold.

The Cow can be killed with a single shot but will disappear and respawn in a few moments. Killing the Cow does not allow you to retrieve any lost credits.