Jellyfish mob

They would spawn in warm ocean biomes and coral reefs, in groups of five. They could come in different colours, like pink, yellow, blue and green. Turtles would attack them. If you touch the jellyfish, you will either take damage or get poison for a few seconds. They would drop jelly which can be made into the jellyfish helmet and wearing it would give you +0.5 armor with water breathing, faster swimming and resistance to the jellyfish damage. Thoughts?