Part three of my never ending series of fish that just brushed up against your leg is the Trunkfish a member of the Boxfish family.
They are essentially hydrodynamic, floating squares with wee little fins and bony armor plates that protect them from prey. The one in hand is a juvenile.
The Trunkfish is basically the turtle of the fish world - a slow moving, creature with protective plates. They come from a family of fishes that secrete a poisonous toxin called ostracitoxin that not only can kill would be predators but can also kill themselves. They don't make good aquarium buddies.
In their natural environment they would blend in well with the sea bottom. In a clear hold tank, not so much.
The white line pattern on this one gives it the appearance of sun passing through water.
Here you can see the tiny little fins that the Trunkfish uses to row its way through the water. They are not fast but with all of that protection - they don't need to be. They may be good whistlers.