Coelacanth
On first glance, the Coelacanth looks like a normal fish. It's long and cylindrical with tail and dorsal fins. It swims in water. That's about where the similarities end. The Coelacanth actually has eight fins: two dorsal fins, two pectoral fins, two pelvic fins, one anal fin and one tail fin. The Coelacanth has a heart shaped like a straight tube and 98.5% of its brain case is filled with fat. The jaw alone — huge and hinged with sporadic teeth — should let you know this isn't something that evolved recently. Thought to have gone extinct 65 million years ago, when it was discovered off the east coast of South Africa in 1938, the Coelacanth became perhaps the most famous example of a Lazarus taxon, a group of organisms that disappears from the fossil record, only to reappear later. That's quite an entrance.