A man could not believe his eyes when a giant bobbit worm akin to a sea monster emerged from behind a rock in his fish tank - after hiding there for two years.

The ghastly creature is captured slithering its way between rocks after the man spotted it while he was cleaning the aquarium's filthy glass.

It is not clear how the 1.2metre worm found its way into the tank but it is common for such creatures to hide in the live coral sold to pet owners.

Lurk: The bobbit worm rears its ugly head after emerging from behind a collection of rocks in the aquarium

Slither: The 1.2metre worm makes its way along the side of the glass tank by arching its body up and down

After capturing the worm in action the man posted the clip, which is filmed in the U.S, on YouTube where it has been watched over 173,000 times.

Maroon coloured with small spiky tentacles along the side of a long ridged armoured body, the worm cuts a striking figure as it glides through the murky water.

It looks more like a creature you would expect to see attacking a crew of intrepid sailors in a science fiction film, than swimming in a fish tank.

At one point you can even see its tail slither away, seemingly having a life of its own, despite being cut off just before the film begins.

After making its way along the glass wall of the aquarium the worm then heads to what looks like the tank's fan and begins to move its way inside.

Bobbit worms, or Eunice aphroditois as they are scientifically known, are ambush predators who have been known to eat fish and coral.

Originating off the coast of countries such as Indonesia and the Philippines, they often hide in rocks and use light and chemical receptors to lunge at their prey.

Mysterious: Bobbit worms are found off the coast of Indonesia and pictured, it shows its colourful underbelly

Giant: The worm glides through the murky water of the aquarium after hiding in the tank for two years

Shelter: The giant worm slithers up to a fan-like object in the aquarium and begins to weave its way inside

Gurutek who posted the video said he had first noticed the worm after his coral began to rapidly disappear.

He said: 'I was breaking down the tank (as I was moving it), hence it looking shoddy. That unice was in there two years before I noticed, and only noticed because I had whole coral colonies missing after a single evening.

'I first saw it after I spent a few nights sat up (after lights went out) for about 3 hours per night looking for the critter who was eating my corals.

'Even when I knew it was there, I only ever saw it 3 times within the space of a year. It hides in the rocks, and only comes out at night, impossible to catch without taking everything out the tank.'