Boreholes in mineralized shells are a widely recognized form of predation throughout the Phanerozoic. In fact, such borings are as old as the first mineralized shells dating back to the Ediacaran. Their occurrence among the earliest skeletal animals has been interpreted that protection against predators was one of the driving forces behind the evolution of mineralized hardparts. Hence, these early traces provide crucial clues in understanding the mysterious emergence of complex multicellular animals. However, new observations made on shells of linguliform brachiopods from the Cambrian of Sweden suggest caution when interpreting perforations in shells as predatory or even as being organic. The recovered acrotretid assemblage is characterized by an unusual frequency of shells bearing circular to irregular circular holes. These holes resemble shell perforations interpreted in the literature as predatory borings and holes produced by a predator using a piercing appendage. However, close examination of the shells reveals the presence of pyrite crystals growing on the shell surfaces and within shell layers, thereby destroying the shell and producing the common perforations. It is proposed that pyrite crystal growth might be responsible for a variety of holes in fossil shells, holes previously interpreted to be predatory.