The cynobacterium (formerly blue-green alga) Nostoc commune sometimes appears in great quantity on bare moist soil, disused roads and concrete paths.
It was commonly believed that it resulted from the remains of shooting stars (meteors), hence it acquired such names as star-jelly in Northamptonshire, star-slutch in Northamptonshire, and star-shot in Lincolnshire and Northamptonshire. The earliest of these names – sterre slyme (star-slime) – dates from 1440. The belief was still current in Cornwall and County Antrim in 1938, and in 1988 was ‘held by some people within living memory’ in north Wales. Similar beliefs, or at least names, have been recorded from Belgium, Denmark, Germany and Holland.
Writing of Cornwall in 1881, Robert Hunt recorded that whenever men working in the granite quarries at Penryn observed a shooting star they ‘went to the spot near which they supposed it to fall, and they generally found a hatful of this mucus’. This seems to imply that Nostoc had some value; was it used as a food?
According to the Austrian phycologist Lothar Geitler (1899-1990) Nostoc was eaten ‘by various primitive peoples’. Other authors record that Nostoc commune var. flagelliforme, which grows in spaghetti-like strings, was collected in the upper basin of the Yellow River in China and transported to Chinese and Japanese cities where it was sold as a ‘gourmet item’. Late in the 1950s it could still be bought, at a high price, in Tokyo. But there are no records of Nostoc being used as a food in the British Isles.

Derived from two articles by Hilary Belcher and Erica Swale:
Catch a falling star, Folklore 95: 210-20, 1984.
A mass occurrence in Cambridge of Nostoc commune Vaucher, a conspicuous terrestrial blue-green alga, Nature in Cambridgeshire 30: 29-31, 1988.

Images: main, Polegate, East Sussex, October 2012, © Ros Sweetman; inset, St Fagans National History Museum, Cardiff, March 2017.

Updated 7 March 2017.