Red Lionfish (a venomous coral reef fish native to Indo-Pacific region) by Bruce Bugbee. Due to the incredible amount of success that Lionfish have while hunting, certain biologists have joked about nicknaming them "terminator fish"
The aptly named Ping-pong tree sponge (Chondrocladia lampadiglobus) is a carnivorous sponge. Those ping-pong ball looking things are covered in tiny spicules which the sponge uses to catch tiny crustaceans.
The reef dwelling clownfish lives in a near perfect symbiotic makes its home within sea anemone. Covered in a thin, mucus-like membrane which protects the clownfish it is able to hide from larger predators within the stinging tentacles of the sea anemone.