Beck-tori

Beck-tori are aquatic parasites that grow to extreme size. The creature resmembles a flat elongated leech. It has rows of scraping spines along the underside of its head that lead to a gaping maw. after using its spines to attach to a living victim, a Beck-tori flexes its body to grind, dislodge, and consume flesh. The creature usually attaches to a large aquatic predator before swallowing parts of it. Eventually, the Beck-tori grinds its way into the victims body cavity, exposing its host to other invasive orgasims. The host's body provides a medium in wich the Beck-tori can lay its eggs before moving on to new prey. Because the movement of a potential host trough the water attracts Beck-tori, they sometimes mistakenly attack boats and submersible craft. Beck-tori larvea are translucent creatures only a few centimeters long. Most pose little danger to anything larger than a normal fish. At their average length, their main treat is their abrasive spikes, altough full-grown specimens can swallow their prey whole. Adult Beck-tori breathe both air and water.

Source

 * Power of the Jedi Sourcebook