The teratological condition known as Ziegler's Blisters is reported for the first time in the pentameroid brachiopod Pentameroides. This reinforces the conclusion that Pentameroides was descended from the genus Pentamerus, which also has the same condition, i.e., Ziegler's Blisters. This is also the first time that a paleoteratological condition has provided evidence to support a previously deduced evolutionary conclusion based on skeletal morphology alone. The relatively shallow, rough water conditions deduced from paleoecologic consideration of the entire fauna accompanying the teratological specimens is supported by sedimentologic data. The fossil locality is from near the base of the Silurian section in the northeastern part of the Mascarene–Nerepis Belt.