Babysitter Snails (Neptunea amianta)
These snails lay eggs in a spiral tower; the adult snail sits on top of the tower until the eggs hatch. Once the juveniles emerge, the parent snail will fall off and die. These snails were first seen clustered together along the SUM1W2 cable route at Southern Hydrate Ridge, but they are found at other rocky outcrop locations around the ridge. The depth at this location was 776 m. These snails have also been found colonizing primary node PN1D at 115 m water depth. The towers appear to be 8 to 12 inches tall and the adult snails are about three inches long.
Paul Yancey, Whitman College, http://people.whitman.edu/~yancey/ https://montereybay.noaa.gov/research/techreports/trtamburri1999.html