Jam-o'-War

Jam-o'-Wars (also referred to generically as jellyfish) are enemies from Super Mario Galaxy. Their name is taken from the, a hydrozoan resembling a jellyfish. They appear in the Deep Dark Galaxy and the Bigmouth Galaxy. They are a large blue variant of Jammyfish. If Mario or Luigi comes in contact with one, he is shocked. They can be defeated only by hitting them two times with a Koopa Shell, and they give one coin when defeated. After they are attacked once, they glow green but do not act any more aggressively.

In Super Mario Galaxy 2, a Jam-o'-War appears in the Cosmic Cove Galaxy. It behaves the same way as in the predecessor, but instead of giving a coin when defeated, it gives ten Star Bits.