Boyorn

Boyorn is an enemy in Mega Man 11 that appears exclusively in Bounce Man's stage. Much like Bounce Man himself, Boyorn was modeled after a rubber ball; it resembles a large green ball with yellow bumps. It was created as an exercise robot for the athletic center/theme park Boing-Boing Park. As such, its outer body is made of rubber, making it so that a Boyorn will bounce around the room whenever it's attacked. It also takes a lot of hits to destroy.

Poyorn
Poyorn is a weaker variant of Boyorn that also appears in Bounce Man's stage, only seen during the battle with Frog Balloon, where three Poyorns spawn once Frog Balloon is destroyed. Poyorns take far fewer hits to destroy because their bodies are made of a cheaper type of rubber, and are colored teal with pink bumps to distinguish themselves from Boyorns.