An aberrant, helicoidal trace fossil Chondrites Sternberg

A helicoidal specimen of Chondrites Sternberg from Upper Cretaceous marly flysch in Switzerland is interpreted as a deep-tier trace fossil. Its producer reworked the filling of a shallow-tier helicoidal burrow that was emplaced earlier, but the earlier trace fossil is not preserved. The aberrant Chondrites was formed by the same tracemaker as the adjacent Chondrites intricatus (Brongniart).