An eater is any still life that has the ability to interact with certain patterns without suffering any permanent damage. The term may also sometimes specifically refer to eater 1, a very common and well-known eater. The block was the first known eater, being found to be capable of eating beehives from a queen bee, allowing the construction of the queen bee shuttle. The animation to the right shows an eater 5 feasting on an incoming stream of gliders.
Eaters are extremely important, as they help stabilize and control debris created by complex reactions, allowing for the manipulation of the useful parts of those reactions. Stable reflectors in particular heavily rely on a variety of eaters to work.