The Horror at Martin’s Beach - Howard P. Lovecraft

When captain James P. Orne and his crew kill a strange and enormous animal in the sea, they are confused. They have never seen anything like this before – the animal looks like a giant sea monster. They start to make money by letting people see the corpse of the animal. Animal experts, however, tell them that the monster was actually only a baby. One day, the corpse disappears... and the animal will have its revenge.