Teacher Karstein Erstad found thousands of live worms on top of the snow . There have been reports of worm rainfall in Norway following his report . Mr Erstad says the 'very rare phenomenon ' happened in Sweden in Sunday .
Teacher Karstein Erstad found thousands of live worms on top of the snow . There have been reports of worm rainfall in Norway following his report . Mr Erstad says the 'very rare phenomenon ' happened in Sweden in 1920s .