Mystery jellyfish sighted off Sydney may be new species

A mystery box jellyfish spotted in Sydney waters may belong to a new species entirely, according to an expert working to identify the marine animal.

Two encounters with the jellyfish were caught on camera by a Sydney resident, who first spotted it last month during a group ocean swim.

The new species has several tentacles around 30cm long and resembles the deadly Australian box jelly, Chironex fleckeri, also known as the sea wasp.