Scrambled egg slime/Fuligo septica/trollsmör, a species of slime mould.
Fuligo septica, commonly known in Sweden as trollsmör ("troll butter"), belong to a remarkable group of single-celled organisms that spend part of their lives as a giant, multinucleate cell known as a plasmodium.
During this stage, they can slowly move across decaying wood, engulfing bacteria, fungi and other microscopic food in their path. It may only travel a few centimetres a day, but it is very much alive and on the move. When conditions change, the plasmodium transforms into a spore-producing fruiting body, which is usually the stage we notice in the forest.
Slime moulds have fascinated people for centuries because they seem to appear overnight and vanish just as quickly. In Nordic folklore, trollsmör was said to be milk spilled by a magical creature known as a bjära or "troll hare", sent out by witches to steal milk from their neighbours' cows. Wherever a little of the stolen milk was dropped in the forest, trollsmör was believed to appear.
The real explanation is perhaps even more extraordinary than the old legends.
Fridenborgshöjden nature reserve in Värmland, Sweden (2 July 2026).
