The Eyeball Frog is a temporary inventory item in Ocarina of Time. It is a Frog with extraordinary large eyes. When the Eyeball Frog is delivered to the Lake Scientist, he will think that King Zora XVI sent it as a delicacy for him to consume.
At the Lakeside Laboratory, while Link is in the midst of acquiring the Biggoron's Sword, he finds that he needs the Eyeball Frog to create the Eye Drops for Biggoron. After receiving it from King Zora at Zora's Domain, he must bring it to the Lake Scientist on horseback for increased speed, as the Eyeball Frog spoils quickly.