A Portuguese Man O’ War (Physalia physalis), isn’t a jellyfish, but it looks a lot like one. It’s actually something called a siphonophore,and it’s a collection of tiny animals living together. Another difference from jellyfish is that it’s got a gas-filled bag so that it floats.
You occasionally see lots of the washed up on the beach after a storm. They can be blue, purple, pink or mauve, and they can be much larger than the ones pictured above with my car keys for scale.
DON’T PICK THEM UP!
They have long tentacles with really vicious stings that stay potent long after the animal is dead. A friend was stung by a big one, and it took four months for the marks to fade completely.
I don’t want to overstate this. They’re rare here (even rarer in the UK, but not unheard-of) because they prefer warmer waters.
Just don’t pick them up.