Terrigenesis

The Terrigenesis is the process that activates certain Inhuman genes allowing the achievement of super powers by inhaling the mist of the Terrigen Crystals.

History
Skye entered a chamber in the temple of the Kree City to stop Raina, but she arrived late, as the Diviner Raina was holding glowed and floated onto a pedestal.

The entrances to the chamber started to close and the Diviner opened, revealing Terrigen Crystals. The crystals grew and released the Terrigen Mist, which caused Skye and Raina to form black, goo-like cocoons and to petrify. After a few seconds the cocoons crumbled, revealing Skye and Raina had unleashed their Inhuman potential.

Trivia

 * In the comics, an Inhuman going through the process of Terrigenesis forms an actual, insect-like cocoon.