Morpha

Morpha, the Giant Aquatic Amoeba is the Boss of the Water Temple in Ocarina of Time, and has complete control over the water in the room in which it resides. This creature seems to be a bouncing red ball that can create long water tentacles to try and grab Link, shake him and throw him across the room, all the while Link is losing hearts. Not much is known about this enigmatic and evil being, but that it drained most of the water in Lake Hylia, and was returned to its normal state once Link beated it. For Link to defeat this fiend, he must take out his Longshot, pull the strange red ball towards him, and slash it. The best place to get Morpha's eye is on the outer edges of the room since you have more free space to dodge his attacks (avoid the spikes on the edges of the room). After defeating it, Link will recieve a Heart Container and the Water Medallion.