Aguamala Jellyfish
Rhizostoma pulmo is known in English as the shiffarms jellyfish. This specimen is a sub-species photographed in the warm waters of the Mediterranean.
In Spain this jellyfish is called aguamala, which means badwater.
This jellyfish is apt to release stinging cells into the water and these can irritate the skin of a person swimming close by. However, stings of this sort are not particularly painful and are only annoying for a few hours. Touching the jellyfish would no doubt cause multiple stings and, in consequence, much more pain; however, this creature is not considered to be dangerous.