What do Americans call this creature?

The first picture shows what we in the UK call jelly and the Americans call jello. The second shows what we call jam but the Americans call jelly.

So what is the American name for the creature in the third picture? We call it a jellyfish because it looks like jelly so do they call it a jellofish because jelly wouldn't make sense in the American dialect as it conjures up images of jam.
What do Americans call this creature?
What do Americans call this creature?
What do Americans call this creature?
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Pic is just a random Google pic of a jellyfish. It's definitely not a man o war, that's more boat shaped with a sail.
What do Americans call this creature?
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