A Morbakka jellyfish has been found caught in mangroves at Mannering Bay in southern Lake Macquarie.
It's a type of box jellyfish, but doesn't have the deadly tentacles found on some of the species.
Council have sent out a warning telling us not to get too close as they do have an extremely painful sting.
Symptoms can include nausea, vomiting, severe lower back pain, breathing difficulties, profuse sweating, severe cramps and spasms.
The sea creature is usually found up in Queensland around Moreton Bay.