A stasis cell is a protoss device used to keep organisms in suspended animation. They could be used for general storage (ex. hybrids), medical storage (ex. Taldarin and Eredas), or even for incarcerating individuals (ex. Tassadar, Mojo and Ulrezaj). They are considered holy by the protoss.
Although an object generally emerged in the same physical condition as when it was inserted the conditions inside the cell might not be perfectly static, especially in cases of imperfect control. Creatures trapped within might emit psionic energy or even communicate psionically with the outside world, as Mojo demonstrated.
The following section contains information from StarCraft: Retribution.