Arista are green Crystals that contains Chakra. It's an Arian-originated material composed of compressed Plavsky Particles.
When they are inert, the Aristas appear as a simple azure colored gem, but even slight emotion, such as agitation, can excite the plavsky particles within. When the emotions of any one of the users reach a significant level, such as strong wishes or desires, all the Aristas would resonate to one another; in doing so, they shine brightly in a golden hue, and can connect the mental thoughts of at least two people. Black Zetsu uses the Giant Crystal to resurrect Kaguya Ōtsutsuki.