Guardian

Guardians are underwater Hostile Mobs that will be added in Update 0.16.0.

Spawning
Guardians only spawn naturally in and around Ocean Monuments. They require Water to spawn.

Drops
Guardians drop 0-2 Prismarine and 0-1 Fish or 0-1 Prismarine Crystals.

Guardians also drop 10 Experience when killed by a player or tamed Wolf.

AI
Guardians swim around in water, attacking any players or Squids that come into sight. They swim in abrupt charges, moving their tail rapidly when doing so. When swimming, their spikes retract. When not swimming they sink slowly and their spikes extend.

Offense
Guardians have two methods of attack: a laser and a defensive thorn-like attack. Guardians primely use the laser, which cannot be dodged and penetrates armor, however when the Player gets too close, they extend their Spikes and deal damage.

Trivia

 * A guardian's eye is actually the "head" part of the mob's model. This gives the illusion of a dynamic eye.
 * Underwater, guardians emit deep, growl-like sounds, but on land they emit high-pitched squeaks. This probably reflects the fact that water can alter sounds.
 * Guardians' laser-beam attacks are affected by the potion of strength, which normally only affects melee attacks of mobs.