Synanceia verrucosa is a fish species, sometimes lethal to humans, which is known as the reef stonefish or simply stonefish

Stonefish

Synanceia verrucosa is a fish species, sometimes lethal to humans, which is known as the reef stonefish or simply stonefish. They are carnivorous ray-finned fish with venomous spines that lives on reef bottoms, camouflaged as a rock...

. They are carnivorous ray-finned fish

Actinopterygii

The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize...

 with venomous spines that lives on reef bottoms, camouflage

Camouflage

Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...

d as a rock. They are the most venomous known fish in the world.
Stonefish live primarily above the tropic of Capricorn: The reef stonefish is the most widespread species of the stonefishes family, and is known to be found in the shallow tropical marine waters of the Pacific and Indian oceans, ranging from the Red Sea to the Queensland Great Barrier Reef.
Stonefish have a mottled greenish to mostly brown colour which aids in its ability to camouflage itself among the rocks of many of the tropical reefs.