Meteorologists and biologists have been left baffled by earthworms raining from the sky over Southern Norway.

According to Norwegian news service The Local, the most recent phenomenon was discovered by biology teacher Karstein Erstad while he was skiing in the mountains.

“I saw thousands of earthworms on the surface of the snow,” he said.

“When I found them on the snow they seemed to be dead, but when I put them in my hand I found that they were alive.”

He thought they might have crawled through the snow, but rejected this idea, as the snow was over half a metre thick across the mountains.

This is not the only time an area experiencing worms raining from the sky in Norway, with other cases found in Molde and Bergen, both in the south of the country.

One popular theory on random animal rain suggest that the worms may have been lifted up by a violent air pocket and then brought back down miles away from where they started.

Another theory says water spouts, weather systems similar to tornadoes, can travel from seas onto land and pick up vegetation, debris, and small animals, carrying them miles away from where they started before they blow themselves out.

Earthworms preserved at The Grant Museum of Zoology. (Peter Macdiarmid/Getty Images)

According to Erstad, it’s not a new phenomenon, with reports of worms raining from skies above Norway dating back to the 1920s.

This rain of worms isn’t confined to Norway either, with a similar case reported at a Scottish Academy secondary school in 2011.

According to a report by STV, a teacher and his students had to take cover during a game of football after worms started falling from the sky.

Teacher David Crichton said: "We were out playing football and had just done our warm up and were about to start the next part of the lesson.

“We started hearing this wee thudding noise on the ground. There were about 20 worms already on the ground at this point."

Crichton told STV he and his colleagues counted 120 worms across the astroturf pitch following the rainfall.

The phenomenon remains a mystery.

Heaven sent: Other falling creatures

* Between AD 77 and AD 79 the Roman writer Pliny the Elder recorded a storm of frogs and fish in his Natural History.

* Showers of live minnow and smooth-tailed sticklebacks fell on Aberdare, Wales, 11 February 1859.

* On 21 May 1921 thousands of frogs fell on Gibraltar during a thunderstorm.

* On 4 March 1998 a shower in Shirley, Croydon, included a large number of dead frogs.

* A heavy storm in Acapulco, Mexico, on 5 October 1967, was accompanied by maggots around 1in long.

* Dozens of fish, later identified as flounder and smelt, were found in gardens and on roofs in the borough of Newham in east London, following a thunderstorm on the night of 27-28 May 1984.

* On 17 May 1996 a fall of more than 20 small fish was witnessed at Hatfield in Hertfordshire.