Skolithos consists of vertical or inclined unbranched burrows that are typically cylindrical. Skolithos-type trace fossils may represent a range of behaviors and widely different producers. They may be a structure built by a mobile organism of small dimension relative to the tube or a protective dwelling structure closely corresponding to the animal's size. A further possibility, which in particular applies to short vertical knobs, is that they may represent an anchoring structure of an organism that otherwise protruded out of the sediment. Such vertical structures are sometimes surrounded by concentric ridges formed by the rotation of the anchored organism (see Jensen et al., 2002). Ediacaran reports of Skolithos are problematic. An interpretation as a basal attachment should be considered for short knobs such as the Skolithos isp. from the Ediacaran of the White Sea area figured by Sokolov (1997, pl. 24:3). Some are short fragments that may as well be the vertical portion of a " Planolites"-type trace (Geyer and Uchman, 1995). The most convincing Ediacaran Skolithos so far described is S. declinatus from the White Sea Area (Fedonkin, 1985). Precise information on its occurrence and a more detailed presentation would be of great interest.

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