These chubby critters live on the sea floor inching their way through the grasses and plants that grow there. Always cheery with a happy smile and friendly word to give, spotting a merterpillar means that you will have a good day. Some wonder whether, like their terrestrial counterparts, they will eventually metamorphose into something else but if you ask a merterpillar they will simply shrug and smile, as they aren't very concerned about what’s going to happen tomorrow.