Jellyfish are found in every part of the sea, from the warm water at the surface to the cold, dark depths of the ocean. Jellyfish eat tiny sea creatures that drift into their tentacles.
Jellyfish come in almost every colour of the rainbow and range in size from smaller than your fingernail to having tentacles that are many metres long.
Some jellyfish are poisonous and their sting can kill a person. It is best to avoid touching a jellyfish if you don't know what sort it is.
Jet, also called lignite, is not a true mineral or stone. It is fossilised decaying wood. The original structure of the wood can be seen in jet under a microscope.
Jet is black and has been used to make jewellery for many years. It was quite popular to make mourning jewellery, for wearing at funerals.
A jigsaw puzzle is a picture that has been cut up into lots of little pieces. Then you have to put all the pieces back together to make the picture. The jigsaw pieces are usually cut into special shapes like in the picture, so they fit together tight and stay together as you are working.
Jigsaw puzzles usually have between 100 and 2000 pieces, and can take a very long time to put back together.