sentences:  This suggests the events leading to inundation - subsidence of land or rising water levels - were extremely quick.Marine investigations in the area have also identified new species of sea anemone, rediscovered the fan mussel (the UK's largest and rarest bivalve mollusc - thought to be found only in Plymouth Sound and a few sites off the west of Scotland) and a number of shipwreck sites, including HMS "Drake", which was torpedoed and sank just off the island in 1917.Rathlin was probably known to the Romans, Pliny referring to "Reginia" and Ptolemy to "Rhicina" or "Eggarikenna".