A poisonous sea creature with toxin potent enough to kill someone in 20 minutes has been seen in the waters off Northland.
The marine snails have previously been seen in the Parengarenga and Whangaroa Harbours.
The cone shells' potentially lethal venom can seep through gloves or a wetsuit, even when handled carefully, the Northern Advocate reported.
Dive instructor Alan Morrison spotted the carnivorous cone shell while diving at Deep Water Cove in the Bay of Islands.
"I was about 300m from the frigate Canterbury when I saw the 6cm-long cone shell. It was about 10m down the bank of an island and stuck to the side of a rock."
Mr Morrison said he photographed the snails.
The cone shells were either herbivores or carnivores, marine expert Wade Doak said.
The herbivores attached themselves to reef crests where they ate algae.
"Carnivorous cone shells, like the one seen at Deep Water Cove, have lighter shells and they fire their weapon at small fish like a whaling harpoon. It's linked to the animal by a translucent tube down which a fatal venom is injected."
The cone shell retracts its tube and draws the prey into its mouth, Mr Doak said.
He said cone shells were capable of killing fish bigger than themselves.
Marine author Tony Enderby said the variety of cone shell found at Deep Water Cove -- Conus lischkeanus kermadecensis -- had been found at the Kermadec Islands and in Parengarenga and Whangaroa Harbours, but nobody in New Zealand had died after contact with them.
