舌形贝（海豆芽） / Lingula (lingulid brachiopod)

My shell shape looks ancient, but my lineage kept evolving—your family photos don’t freeze evolution either!
我的壳形看着古老，但我的支系一直在演化——你的家族照片，也不能把演化按下暂停！

Sources
The Lingula genome provides insights into brachiopod evolution and the origin of phosphate biomineralization
https://www.nature.com/articles/ncomms9301
Oxygen equilibrium of brachiopod Lingula hemerythrin.
https://doi.org/10.1126/science.132.3426.550
Species reference
https://en.wikipedia.org/wiki/Lingula_(brachiopod)

Research context
Lingulid brachiopods illustrate the persistence and change of an invertebrate body plan. They help place vertebrate evolution in a broader ecological history; a similar shell shape does not imply evolutionary stasis.