From Destinypedia, the Destiny wiki
The Descendants (or Sol Imminent), are a Vex collective spanning from the far future of the Vex network, having first been encountered within the Vault of Glass. They can be identified by their black and brown-colored frames and ring-shaped heads. 
According to multiple Ghost analysis, these Vex are extremely old, in that they have been active for an incalculable span of time—indicating that they may very well have come from the future. Gorgons are also members of this collective.
List of appearances