A shell marisa variant that uses a clam shell instead of the usual oyster shell. Being a shell marisa variant, they're still referred to in-universe as "shell marisa" or "shelly" instead of "clam".
An extremely rare yukkuri, being an even rarer variant of the already rare shell marisa. Their extreme rarity is due to their life expectancy being even lower than the already low oyster shell marisa for obvious reasons.
Barely capable of moving or cleaning their own excrements, they're virtually incapable of surviving outside of captivity. Despite rare species usually being popular with humans, clam marisas, just like the regular shell marisas, are often neglected by humans due to how high maintenance they are as pets.
Just like regular shell marisas, clam marisas often dreams of living underwater where they can swim and is actually capable of thriving. Just like regular shell marisas however, it's unclear whether or not clam marisas can actually swim underwater or even if they can survive being submerged.
They tend to get along with regular shelled marisas due to both technically being the same species