Bari

Bari are huge gelatinous masses equipped with an electric offensive attack. They are found in Ocarina of Time, Oracle of Ages, and Twilight Princess.

Ocarina of Time
In Ocarina of Time, these electric monsters can be found Inside Jabu Jabu's Belly or in the Gerudo Training Ground on Master Quest and will electrocute Link on contact. They hide above their prey and drop down on individuals who wander across their path. Bari are parasitic creatures who can only survive inside the body of a living host. Thus the Bari survived in Jabu Jabu's belly. They can only be defeated by using the Boomerang (or weapons such as the bow on Master Quest). Once defeated, it will split into a trio of Billy, which can also only be bested by the Boomerang.

Oracle of Ages
In Oracle of Ages, Bari make an appearance and take a similar role as they did in Ocarina of Time. They appear only in water areas and can be found all over Jabu-Jabu's Belly. When defeated, they split into two smaller enemies known as Billy.

Twilight Princess
In Twilight Princess, these enemies are located in the Lakebed Temple. Unlike the Bari found in Ocarina of Time, they are found exclusively within bodies of water behaving more like jellyfish. When Link approaches one, they generate an electric field around them that acts as a shield, but lasts for a short time. When the shield is gone, Link can Clawshot the Bari to take out their nucleus.

Trivia
Bari from Twilight Princess are freshwater jellyfish, which is unusual since almost all jellyfish live in saltwater.