From Destinypedia, the Destiny wiki
Clarity Control is a veiled figure, identical in appearance to those found in the Black Garden, the Lunar Pyramid, and the Europan Pyramid. Unlike these others, which seem to be merely inanimate statues, Clarity Control exhibits slight movement: the lower folds of its cloak move slowly, and its chest region rises and falls in a way that suggests that it is breathing. The figure is suspended in midair, and appears to be surrounded by a forcefield that selectively repels certain objects, such as fallen snow and ice; the tunnel in which it is located suffered a cave-in at some point, but an ovoid volume around the figure remains clear of debris.
The statue had arrived on Europa roughly twenty years before Clovis Bray's discovery buried beneath the icy surface. Attempts to move Clarity Control from its location would instead trigger a "violent reaction" to Braytech research teams, resulting in the deaths of nineteen researchers. Instead, the Clovis Bray corporation decided to build their facility surrounding the statue itself, which then became the Deep Stone Crypt.
Clarity Control was used to combine Darkness (referred to as "Clarity" by Clovis I) with Vex Radiolaria to create Alkahest, a primary ingredient in the creation of the Exo. Clarity Control, in Clovis I's words, is the source of Clarity.