Abstract
Synopsis: Detailed descriptions are given of the trace fossils Skolithos and Monocraterion in the Lower Cambrian Pipe Rock, which have hitherto been referred to as ‘ordinary pipes’ and ‘trumpet pipes’ respectively. They are interpreted as the dwelling burrows of the same type of suspension-feeding worm-like organism. Skolithos was probably formed during periods of negligible sedimentation, whereas Monocraterion probably resulted from upward movement in adjustment to influxes of sediment.