Sea pens (order Pennatulacea)
… are colonial marine cnidarians. There are 16 families within the order; they are thought to have a cosmopolitan distribution in tropical and temperate waters worldwide. Sea pens are grouped with the octocorals (“soft corals”), together with sea whips and gorgonians.
The sea pen fossil record is patchy and disputed; while the earliest accepted fossils are known from the Cambrian-aged Burgess Shale (Thaumaptilon), similar fossils from the Ediacaran (ala Charnia) may represent the dawn of sea pens. Precisely what these early fossils are, however, is not decided…
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