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.
Multicolored Nudibranch Photograph by Mohammed Alsaleh, My Shot Generally oblong in shape, nudibranchs can be thick or flattened, long or short, ornately colored or drab to match their surroundings. Some max out at a quarter of an inch millimeters)
*SAGAMINOPTERON PSYCHEDELICUM NUDIBRANCH ~ Originally described from Guam, this animal is now known from many parts of the tropical western Pacific Maximal size : 20 mm. Frequently on the reef flat zone and the fore reef zone. (psychedelicum, indeed.