The Tentacle Biome is a very unusual biome made out of giant tentacles.

Always a big or (rarely) medium size planet.

Sugarcane plants may be found. Tentacles drop unrefined wood with no sapling so they are not reproducible. The only shrubs in this biome appear as  small clusters of tentacles and will not drop anything (yet).

Acid rain happens quite often.

The ground in the tentacle biome is mainly made up of a pinkish, yellowish or reddish dirt that will make a squishing noise when walked on. On top of the dirt is a layer of brains, which are currently unobtainable unless creative mode is used.

The Tentacle Biome is most likely the remains of a planet attacked and destroyed by the Ruin. Another possibility is that the Tentacle Biome was a beta version of the Ruin itsself.

Materials: Corrupt Dirt, Dire Stone, Cobblestone, Corrupt Water.

These biomes can be found in any sector.

According to the Human introduction video, the Earth was reduced to one large tentacle biome 

Giant Cephalopod