This is a Zebra shark. It's a lesser-known shark, at least to me, because it's not one of the faster, toothier ones. It's a low-key shark that sweeps the bottom of the reef for crustaceans and such. Anyway, they are a creature with the most pleasing shapes I can think of. Look up a picture and you'll see that they are a complex collection of straights and curves that can change dramatically depending on the viewing angle.
They have stripes when they're young, hence the name. And spots when they grow up, being also known as the Australian Leopard Shark.
And they are not blue. That was me.