Although the record of Paleozoic drillholes is long and extensive, evidence pertaining to the identity of the drillers is sparse. The most conclusive evidence, a driller "caught in the act", has been documented only once (Baumiller 1990). In that example, a drillhole in the calyx of a crinoid was found directly beneath an attached platyceratid gastropod. Additional evidence for drilling by platyceratids has been circumstantial, i.e., based on the association of platyceratids with certain blastoids and crinoids, and the presence of drillholes in other crinoid and blastoid taxa. To a skeptic, the lack of congruence between drilled and platyceratid-infested crinoids and blastoids is not sufficient evidence that platyceratids were the drillers. More conclusive evidence requires examples of drillholes in taxa that are known to have been platyceratid-infested, preferably from localities where both infested specimens and drilled specimens co-occur.