The Algerian Sea Centipede is an aquatic, centipede-like crab.It's about the size of a whale, is an amphibious, and can crush entire ships. It is primarily an invertabrate but is also somehow Chilopoda in origin since it is part centipede.One well documented encounter was in May 21, 1899 - Cape Falcon, near Mers-el-Kebir, Algeria.
This sighting in the Mediterranean occurred when sailors aboard the H. M. S. Narcissus, saw a creature they said was 150 feet long, near Cape Falcon, Algeria. Lieutenant Boothby was on watch at 5 A.M. when he observed a “sea monster” from the port bow. He wrote in the log that it was “propelled by large fins, and lying very low in the water.” Boothby and sailors on board observed it for thirty minutes. A London newspaper reporter asked one of the sailors if he did not think it wasn’t a line of porpoises. The sailor said that they has seen “some porpoises just after and their motion was not the same. You could see the porpoises jump and tumble over, but this creature lay steadily on the surface, gently gliding through the water.” The signalman witness reported the monster was “propelled by an immense number of fins.” The movement of the fins was strong enough to keep the creature thrusting along at the same speed as their ship. He noticed the fins were on both sides of the animal, turned over and over, and were located all the way to the tail. The head could not be seen because of the water being kicked up by all those fins. Curiously, the animal “spouted up water like a whale, only the sprouts were very small and came from various parts of the body,” one witness recalled. Heuvelmans speculates that some of this water seen spraying up was “splashes raised by rows of fins along the sides.”