Magma Cube

Magma Cubes (Sometimes called slimes of the Nether) are hostile mobs that spawn in the Nether dimension. They will probably be added in 0.10.0, with the addition of potions as their drop, Magma cream as key ingredients in the potion of Fire Resistance. Magma Cubes somewhat resemble slimes and also split into many smaller Magma Cubes, but are reddish-brown in colour and unlike slimes, the smallest size can also attack the player.

Combat
Magma Cubes are mostly found in or around Nether Fortresses. They are immune to lava and fire and also do not take fire damage. Also, due to their Natural armor rating, they can be tough to fight, specially the largest ones, who have about 31 health (15.5 hearts). However, with an iron or diamond sword, they can be defeated in about 3-5 hits. Unlike slimes, even the small magma cubes do damage, so the player should not ignore the small ones.

Trivia

 * Large Magma cubes can even jump over four block high structures.
 * Magma cubes do not take damage from water.