The Cosmic Beings were nine individuals who attempted to wield the Power Stone.
This group attempted to harness the abilities of the Power Stone by sharing its power between them, achieving this through linking themselves together. The effects were short-lived, however, as the energy of the stone disintegrated all of them after a few moments.
The Collector showed a projection of this event to the Guardians of the Galaxy as he explained the history of the stones to them. As the Collector uses a projector to show what happened to cosmic beings and gives details on the event seen in front of everyone. The Guardians are look at the projection in shock witnessing the power of the stone.