And a second one that doesn't have any evolutionary form as well, Shuckle is a dual type bug and rock Pokemon.
I don't know what kind of bug Shuckle is but it looks more like a worm ^^. It has a soft yellow body and four legs (or arms?), lives inside a hard, red shell which has eight holes / openings on which it can stick its limbs and head out. Shuckle first appeared in Pokemon Gold and Silver.