Skogs-Tibble parish near Uppsala is unusually rich in Bronze Age sacrificial finds, so I’m looking closer at it for some future fieldwork. And I found an awesome site in the Sites & Monuments Register, Raä Skogs-Tibble 93:3:
Skrubbstenen [The Scrubbing Stone]. Boulder with oral tradition, granite, c. 4 by 4 m a side … According to Ivar Hall, 80 years old, of Sågstennäs, his maternal grandfather told him that trolls used to scrub and delouse themselves against the inward-sloping side of the boulder in the two cavities there.