These are not true jellyfish, but siphonophores - colonies of smaller organisms called zooids, each with their own specialized function and dependent upon each other. The float is pink to purple in colour, up to 10 inches long and can be deflated allowing it to submerge. The tentacles may reach several yards in length and can inflict a serious sting. Once a rare visitor, but becoming more common. The treatment for stings by this animal is to immerse the affected part in hot water (as hot as the casualty can stand) for about 20 minutes.
Found at : Pembrey Beach, Carmarthenshire