According to a 2003 research paper which studied the hippocampus brain activity in saltwater invertebrates, we should be saying "happy as a lobster". On a scale of 1-10, lobsters rated 8.7, crabs 7.9, mussels 6.2, sea urchins 4.3, and clams came in almost dead last at 2.6. The only thing sadder than clams were scallops at 2.5, but that could be within the margin of error.
