Pipe Rock Trace Fossil

Trace fossil produced by unknown biota but phoronids or annelids are suggested as creators. "The makers of early Cambrian S. linearis were typically gregarious, living in sand sheets and bars in nearshore, tidally-influenced marine environments, where their activities are recorded by so-called pipe rock. These tubular dwellings (domichnia) were probably inhabited by suspension- or deposit- feeding worms, most likely phoronids or polychaetes, although later occurrences of Skolithos ichnospecies may represent the activity of a wider range of producers belonging to different phyla." (Knaust et al, 2018)

"Skolithos is one of the most widely reported trace fossils. It is also one of the earliest defined valid ichnotaxa, the first named in North America, and the first based on North American material. Moreover, it characterizes the littoral to shallow sublittoral Skolithos Ichnofacies (Seilacher, 1967), widely recognized by sedimentary geologists. Today, Skolithos is reported to occur globally in Cambrian to Holocene strata, representing continental to deep-water marine paleoenvironments. Partly on this account, Skolithos presents challenges with respect to its diagnosis and description. According to current understanding, Skolithos is a simple, sub-vertical, unbranched, cylindrical tube with or without a lining, and passively filled. This characterization is problematic because of its weak diagnostic features. As a result, the ichnogenus Skolithos has become a “wastebasket,” embracing forms (more than twenty of them recognized as discrete ichnospecies) that were likely produced by a variety of organisms belonging to different metazoan phyla, and possibly including even plants. Consequently, given its very general definition, Skolithos has lost much of its original usefulness as a paleoenvironmental indicator" (Knaust et al, 2018)