Jellyfish are marine invertebrates. The body of an adult jellyfish is composed of a bell-shaped, jellylike substance enclosing its internal structure, from which the creature's tentacles suspend. Each tentacle is covered with stinging cells that can stun or kill other animals. Most jellyfish use them to secure prey or as a defense mechanism. Most jellyfish are passive drifters that feed on small fish and zooplankton that become caught in their tentacles. Jellyfish have an incomplete digestive system, meaning that the same orifice is used for both food intake and waste expulsion. This series of "Marine Life Protection" proof one dollar coins has been a hit with collectors since the first coin was issued in 1992. It is hard to say whether the obverse or reverse is the most attractive, but they are becoming exceedingly hard to find. Palau was chosen as the location for the 10th season of the hit reality series Survivor, and this coin depicts regional marine life, as well as a beautiful mermaid. This One Dollar coin is legal tender and has been issued by authority of the government of Palau.