Alien in a can creates trauma in the kitchen

When you open a tin of tuna the last thing you expect to see is a head staring back at you.

So Zoe Butler of Nottingham in the UK was more than a little perturbed to find that, nestled within her sandwich filling, was a tiny sea creature.

Dr Hany Elsheikha, associate professor of veterinary parasitology at the University of Nottingham, said it could be a juvenile crab.

But the tiny tuna monster has set Twitter abuzz with explanations and the mystery has been dubbed #tunagate.

Mark Dodds suggested it was the Cymothoa exigua, or tongue-eating louse. The parasite lives inside a fish, entering through its gills and attaching itself to its host's tongue.

Others speculated that it could be the foetus of a blowfish, a tadpole, a copepod or the head of a soft-shelled turtle. Elliot Sambells said: "It's clearly some sort of alien."

Butler, 28, bought the can of tuna from an Asda in Arnold, a suburb of Nottingham. "I opened the lid and saw a purply thing, a gut sack or intestine. Then I turned it round and pushed it with a fork and saw it looking back at me," she told the Nottingham Post.

"I dropped the fork, jumped back, and screamed a bit.

"It's got like a spiny tail along the bottom. It's quite grim."

The Natural History Museum, in London, goes along with the tongue-eating louse conjecture.