Name a sea animal that isn't a fish or a bird

Why these answers count

The scoring here is unusually flat: almost every recorded answer sits at 85, which tells you the judges rewarded a real, specific, correctly spelled name and stopped there. The single 100-point entry, Hoff crab, is the exception that proves the rule, an oddity memorable enough to stand out from eleven thousand competent picks. At the other end, the 348 answers on 60 points are the ones that stayed generic, a bare group word or a vague label that could cover dozens of different creatures. Between those poles, the 85-point field is dominated by precise two-word names, from the plainly descriptive Abyssal murex and Acorn barnacle to the more specialist Abalone piddock and Abalone barleysnail, and it even stretches to a marine mammal such as African Clawless Otter. The lesson is that detail pays as long as it is genuine: reaching one level below the everyday category name, and getting the spelling right, is worth far more than picking something famous.