A berry crushed into service as a metaphor for a mud-mark.

‘Tarka’s deep seals in the lower ooze showed like big blackberries crushed in the mud.’

Source: Henry Williamson, Tarka the Otter: His joyful water-life and death in the two rivers, illus. C.F. Tunnicliffe (Harmondsworth: Puffin Books, 1976 (1927)), p. 147

Photo credit: ulleo at pixabay.com