As you're swimming in the ocean, you notice something that looks like stained-glass floating in the water. It is, in fact, a jellyfish creature and not a window!
Jellytons are a stained-glass jellyfish that live close in the coastal waters of Ark. Because they're glass, they cannot sting you in the conventional sense—instead they can severely cut you. Getting cut by a Jellyton is terrible as it is... but if you start bleeding you will begin to attract nearby sharks, too, in the water.
Jellytons, otherwise, are absolutely beautiful to look at and flocks of them grouped together can change the color of the coastal waters if they're close to the surface. This effect is stunning at sunset in particular.