teratoma. [terâ²ÉtÅâ²mÉ] pl. teratomas, teratomata. a tumor composed of different kinds of tissue, none of which normally occurs together or at the site of the tumor. Teratomas are most common in the ovaries or testes.
The pink-colored film or ring frequently seen on showers, tubs, toilets and pet water bowls is typically caused by growth of the airborne bacteria Serratia marcesens. This harmless nuisance organism reacts with standing water and frequently forms during spring and summer months.
And if you have stubborn mineral stains, it's even more of a pain. Believe it or not, mineral and rust stains in your toilet or tub -- greenish stripes, a brown ring, lime scale -- aren't caused by anything you're doing wrong in your cleaning regimen. It's simply something in the water.