Eye worms are blue alien worms which possess a defense mechanism that, if entered into a planet's food chain, will cause the sterilization of all affected creatures.
Rick had a whole group of eye worms in his garage in the episode Vindicators 3: The Return of Worldender and tasked Morty with capturing them. he wished to save the worms in case he should want to sterilize a whole species. After they were called by The Vindicators, an eye worm was picked up and flown away by a bird; entering it into Earth's food chain.
The eye worms are small blue worms one huge yellow eye which is extremely large compared to the rest of the body. They possess six legs on the upper side of their body and none on the lower. The upper body has deep blue color, while the loer part has a darker blue color with thin stripes of the same blue as the upper.
Eye worms are very fast considering they are worms with small lags legs relative to their bodies. They can crawl up walls and on ceilings, and wherever they go they leave tracks of light-blue slime. Their defense mechanism is that if they enter a planet's food chain, all affected creatures will become sterilized.