Miscellaneous morphological features for comparisons A preserved Ophiophragmus wurdemanii, mouth with buccal funnel B live Ophiomastix wendtii, mouth with buccal funnel C SEM of Asteroschema brachiatum proximal vertebra end, hourglass-shaped streptospondylous articulation D SEM of mid-arm vertebra of Ophiocomella sexradiata, ventral, with lateral ridges for connections to VAP E SEM of LAP of Ophiothrix angulata, 6 thick spine articulation lobes oriented diagonally F SEM of Ophiactis savignyi string of 5 pairs of very wide LAPs attached to Vs with intervertebral muscles, Vs attached to Vs with ligaments. Abbreviations: IL – intervertebral ligaments, IM – intervertebral muscles, LAP – lateral arm plate, LR – lateral ridge, V – vertebra.