The problematic bodies Pieninia oblonga Borza & Misik common in Barremian to Upper Eocene shallow-water sediments were considered as algae, rudist fragments, echinoderm remains, or sclerites of Gorgonaceae. They were recently found inside the skeleton of sponges, probably Keratosa. The growth stages of these bodies are described. The question remains whether they are unusual sclerites or parasites. The way of their loosening from the skeletons was not observed.