Every so often a decayed corpse of an unidentifiable animal washes up on a beach somewhere and locals are stricken by its ressemblance in shape to a plesiosaur, the long-necked aquatic dinosaur which the Loch Ness Monster is believed to be. It is inevitably determined to be a dead basking shark, which can be up to 45 feet long, and whose most shark-like features (the jaws and dorsal fin) rot away soon after death, leaving behind something which looks coincidentally like a plesiosaur.