Millistoma

Millistoma are a very rare and very large species of carnivore native to Saturn. They are the only animals known to prey on or otherwise threaten Rukhs, and thus serve as a feared mythological figure in Rukh tradition.

Anatomy and physiology
Millistoma are the largest organisms to inhabit Saturn and the largest in the Solar System. Their exact size is not known, but one individual was the size of "a small [U.S.] state", indicating a width somewhere in the area of 160 kilometers (100 miles). Millistoma consist of thousands of smaller components, each with a large, toothy mouth, all arranged in an amorphous mass. A Millistoma's body can shape itself into a gigantic "bowl" in order to catch prey, or into "hills" and "valleys" when more precision is required.

Diet
Millistoma spend most of their lives feeding on the decaying remains of other Saturnian life forms that fall into the atmosphere's depths. However, during the summer, they rise into the warm equatorial regions in order to feed on living prey. They seem to prefer hunting Rukhs, devouring entire flocks at once.

Environment
Millistoma inhabit a different region of Saturn than its other inhabitants. They dwell deep below the ten-bar water cloud layer, in a much hotter layer of the atmosphere that likely lies close to where it transitions to liquid hydrogen. They spend most of their lives here, feeding off dead animals that fall to these depths.

Appearances

 * Saturn Rukh, by Robert L. Forward (1997)