The grey side-gilled sea slug (Pleurobranchaea maculata) might look unassuming, but it holds the title of Aotearoa’s New Zealand’s most toxic creature.
The slug contains tetrodotoxin (TTX), the same deadly toxin found in pufferfish, and its skin has the same pH as that of a car battery.
If you see a grey gelatinous blob washed up on the beach in your area, give it a wide berth and inform your local council.