Pycnogonids are abundant on many sulfide structures in the vent fields within the caldera of Axial Seamount. These 8-legged arthropods are commonly found in areas where venting has stopped, leaving variably oxidized edifices. Here, they are associated with snails and a small scale worm ~ 1 cm in length. Credit: NSF-OOI/UW/ISS; Dive R1836; V15.