The Ood.

The Ood were a humanoid species with coleoid tentacles on the lower portions of their faces. They have no vocal chords and instead communicated by telepathy. This telepathy is perceived as song. They were originally a hive mind led by the Ood Brain. This kept control of the two brains in each Ood (a forebrain embedded in their body, and a secondary hindbrain connected by an umbilical cord-like connection to their faces, usually held in their hands). The hindbrain enabled them to connect to a single large brain, which coordinated individual Ood.