Comment by QuezBird on Notes From an Apocalypse · 2017-09-24T08:57:14.568Z · LW · GW

I enjoyed the article. It seems like you gave sea urchins as an example of a mollusc, when in fact sea urchins are echinoderms, just like starfish. So they are actually Deuterostomes (like us!). The common ancestor of us and molluscs is the same as the common ancestor of sea urchins and molluscs.