Each red plasma bomb is a large black and dark grey sphere. Encircling them on one of their upper hemisphere is a red stripe with a couple of smaller white stripes inside it.
During the "Bauble Battle" edition of the "Egg-Mania" event, the red plasma bombs were redesigned as red baubles with the Eggman Industries logo on them. They were also referred to as "red baubles."
The red plasma bombs only appear during events where Eggman can be fought. In gameplay, Eggman randomly drops them from his Eggmobile in front of the playable characters as they run. If the playable characters makes any form of contact with the red plasma bombs, they will inflict damage, unlike the blue plasma bombs which can be deflected with a spin attack.