The leafy sea dragon, Phycodurus eques, is a marine fish related to the seahorse. It is the only member of the genus Phycodurus. These creatures are native to the waters around southern and western Australia and generally remain in shallow, temperate waters. Their name comes from their appearance, with long leaf-like protrusions coming from all over the body. These protrusions are not used for propulsion; they serve only as camouflage. The leafy sea dragon propels itself by means of a pectoral fin on the ridge of its neck and a dorsal fin on its back closer to the tail end. These small fins are almost completely transparent and difficult to see as they undulate minutely to move the creature sedately through the water, completing the illusion of floating seaweed.
Much like the seahorse, their name comes from a chance resemblance to a known (in this case mythical) creature. While not large by sea monster standards, they are very large for sea horses, growing at least 18 inches (45 cm). They feed on plankton, algae, and other small flotsam, and are not preyed upon by any species other than humans. Females deposit eggs on the tail of the male where they grow to maturity. They have become endangered through pollution and industrial runoff as well as collection by fascinated divers who are entranced by their unique appearance. In response to these dangers they have been officially protected by the Australian government.
A related species is the weedy sea dragon, which is green and grows weed-like fins and can be much smaller than the leafy sea dragon, although according to the November 2006 issue of National Geographic magazine, leafy and weedy sea dragons may be the same species residing in a wide range. (wikipedia)
Leafy Dragon Seahorse, Dallas World Aquarium.