Aurelia aurita

Jellyfish are amazing ocean animals that float and pulse in the water. They don't have brains or bones, and their bodies are mostly water! But be careful, because their long tentacles can sting if you touch them, so it's best to look but not touch.
Whoa! Jellyfish have been around for over 500 million years, even before dinosaurs roamed the Earth!
This one is venomous, which means it can put venom into you with a bite or a sting. Never touch it, and never try to move it yourself.
Always ask a grown-up before you touch any animal or plant. If something bites or stings you, tell an adult right away.
Source: FWC
Read more about the jellyfish at Wikipedia.