noun
brachiopod
A taxonomic term for marine invertebrates with bivalve-like shells, distinct from bivalve mollusks. Used in biology and paleontology.
腕足類は古生代に繁栄した海の生き物です。
Brachiopods are marine creatures that flourished in the Paleozoic era.
二枚貝 refers to bivalve mollusks (e.g., clams, oysters), while 腕足類 are brachiopods, a separate phylum with a different internal structure.
From 腕 (wan, 'arm') + 足 (soku, 'foot') + 類 (rui, 'group'), referring to the arm-like lophophore used for feeding. The reading わんそく is a standard on'yomi compound.