The aliens first appeared on episode 416 of The Muppet Show, in which the pair hatched from a meteor that has crash landed in the backstage of the Muppet Theater. They were performed in this appearance by Frank Oz and Dave Goelz.
The alien puppets have eyes that blink side-to-side.
They appeared in The Muppet Show Comic Book: Pigs in Space.
The puppets were used in various roles on Mopatop's Shop.