The bell has a number of small white or yellowish warts with stinging cells, and near the margin, equidistant from the tentacles, are four rhopalia (sensory structures with ocelli).

Taxonomic reviews have shown that most of these are other species in the genus Carybdea, with the true C. marsupialis essentially restricted to the Mediterranean Sea.

[4] Carybdea marsupialis is a predator and feeds on invertebrates and even small fish which it captures with the nematocysts (stinging cells) in its tentacles, often in shallow waters.

[4] In severe cases, the symptoms can be systemic, including pain at the sting site and elsewhere, paresthesia, hyperesthesia and skin lesions, and may take a few months to fully disappear.

During this mobile stage, pieces may become detached or the cubopolyp may split transversely; these fragments regenerate their missing parts within 72 hours.