For 10 points, name this phylum that includes octopi and clams.
Organisms in this phylum have chemosensors known as osphradia, and the scaphopods in this phylum contain light-sensing organs known as aesthetes. This phylum's second-largest class is sometimes called Pelecypoda because organisms in that class apparently look like hatchets. A unique class within this phylum has a closed circulatory system and contains the lowest organisms thought to have a "true" brain. In addition to (*) Bivalvia and Cephalopoda, other classes within this phylum include Gastropoda, which contains slugs and snails. For 10 points, name this phylum that includes octopi and clams.
Organisms in this phylum have chemosensors known as osphradia, and the scaphopods in this phylum contain light-sensing organs known as aesthetes.
{Mollusca} [or {mollusks}]