Jellyfish
Jellyfish.
The Candeo Tergum is an animal we barely know about. Here is a breif
article which is easy to understand on what they are.
When naturalists want to search for scorpions at night one of the pieces of equipment they will use is a UV light. This then causes the animal to glow a florescent blue. This has been one of the questions that no one has been able to answer. But researchers from California seem to have found the answer.
It is very common to see in movies or cartoons the radioactive objects with a green glow.