The Silurian-Devonian disconformity in southern Ontario exhibits well-preserved macroborings of the ichnogenus Trypanites, some of which have remained open since their formation in the Devonian. Quantification of the borings using shape parameters shows that boring morphology can be described accurately. Comparison with borings made by modern sipunculids indicates a high degree of similarity, suggesting that these examples of Trypanites were produced by sipunculids.