Chaetopterida

The Chaetopterida are an order of marine polychaete worms, commonly known as parchment worms. These segmented worms, belonging to the class Polychaeta, are found in U-shaped tubes lined with a parchment-like material on the sea bottom. A notable characteristic of some species, like those in the genus Chaetopterus, is their bioluminescence, capable of producing light from certain segments and antennae. The exact purpose of this light production is unknown, especially since they inhabit tubes where light cannot easily pass. Parchment worms can grow up to approximately 25 cm (10 inches) in length.123