Neopolynoe chondrocladiae

Neopolynoe chondrocladiae can have up to around 94 segments with 15 pairs of elytra that bear a marginal fringe of papillae. The lateral antennae are inserted ventrally to prostomium, directly beneath the median antenna. The notochaetae are distinctly thicker than the neurochaetae and possess only simple tips.^[4]

Neopolynoe chondrocladiae has an obligate symbiotic relationship with the sponges Chondrocladia robertballardi and Chondrocladia virgata.^[4][5] The nature of the symbiotic relationship has been debated, but a 2021 study using a multidisciplinary approach suggested that the relationship is mutualistic, proposing that Neopolynoe chondrocladiae may use bioluminescence as a lure for prey which is consumed by both the worm and its sponge hosts.^[5]