Old Crabby is a hermit crab who appears in the 1986 book Kermit the Hermit. He arrives at Baby Kermit's cave for the hermit convention, and promptly seats himself on a boulder. From there, he tells Kermit about the wide variety of hermits in the world, and they arrive as he mentions them. The old crab uses a lorgnette (spectacles on a stick) to see out of.
When Baby Kermit awakens, it's revealed that an alphabet block with a C for crab inspired the character.