Worms

The Worm is an animal in the television series Adventure Time with Finn and Jake.  

It makes its first appearance in the episode Evicted. A worm first appears on Finn's bed, and begins attempting to hypnotize Finn when seen. Finn simply throws a book at the worm to knock it off. Later, when the boys are given their house back from Marceline, they find it is infested by many worms including the Giant Worm King. The Worm later appeared for a quick cameo scene at the start of Tree Trunks (episode).

Appearance
All of these types of Worms are small and green with stripes running down their body. They also look similar to their king.