COTSBot is a 30-kilogram yellow torpedo with a maximum speed of over 2 meters per second and an endurance of over 6 hours. Five thrusters give it the capability of briefly hovering in the water column, giving it time to attack crown of thorns sea stars with an integrated poison injection system. It's completely autonomous, down to the identification and targeting of COTSS lurking among coral. [...]
When these outbreaks happen, swift and comprehensive eradication becomes a priority to keep reefs intact, but human divers can only manage to kill about 120 sea stars per hour with poison. Last year, a much more effective poison was developed at James Cook University in Queensland, Australia, called thiosulfate-citrate-bile salts-sucrose agar that can kill a COTSS in 24 hours after a single injection, causing "discolored and necrotic skin, ulcerations, loss of body turgor, accumulation of colourless mucus, loss of spines [and] large, open sores that expose the internal organs."
Poison-Injecting Robot Submarine Assassinates Sea Stars to Save Coral Reefs