Jellyfish are very sneaky about stinging. Most are silent. Some have venom that kicks in on a time delay. Many species even manage to get in a few zingers after they’re dead.

But according to research published Thursday in Communications Biology, the stealthiest stinging strategy belongs to Cassiopea xamachana, a species of upside-down jellyfish found in the Caribbean Sea, the Gulf of Mexico, and warm parts of the Western Atlantic like the Florida Keys. When disturbed, this creature acts like a space-movie mother ship — it emits tiny balls of stinging cells that then swim around on their own, zapping anything in their path.

These “self-propelling microscopic grenades,” which the researchers have named cassiosomes, also appear to stun and kill prey for the jellyfish, said Cheryl Ames, an associate professor at Tohoku University in Japan and lead author of the study.

The finding is “paradigm-shifting” and will change how researchers think about how jellyfish eat and sting, said Angel Yanagihara, a jellyfish envenomation expert at the University of Hawaii who was not involved with the study.