An eight year old boy has been left with nasty red scars after being badly stung by a dangerous Portuguese man-of-war jellyfish.
Jonathan Asplin was swimming in a rock pool in Ilfracombe in Devon when he was stung, and was taken to hospital for the sting.
He was injured on his lower leg, but was luckily protected from being further hurt by his wetsuit.
The jellyfish normally live in warmer waters, but can drift to our shores.
They're also known as bluebottles
Their tentacles can be as long as half a football pitch
They got their name because their airbags can look like the sail of an old Portuguese warship
The sting doesn't usually kill - but it REALLY hurts!
The man-of-war is made up of a lot of tiny creatures which live at the bottom of an airbag, which floats. They form one big jellyfish.
Underneath the airbag are tentacles, where the creature's stings are, and these are used to catch food.
They are very rare around the beaches of Britain.