Sorry about the spelling, Anomaclaris was the worlds first apex predator. It lived BEFORE fish even existed.
It had awesome eyesight and grew to about as big as a juvenile Megalodon. It did not look like any predator seen before, in fact it really looked like a sea monster shrimp as it had a shell. It had claws, the biggest diet of its time period, nothing would take on its rathar large body and it swam like a dolphin(by flapping its tail up and down)