Lower Cambrian cavity-dwelling endolithic (boring) sponges

In the Lower Cambrian Forteau Formation (middle Bonnia–Olenellus zone) of southern Labrador, cavities in archaeocyath patch reefs contain preserved coelobiontic endolithic sponges. Scallops and carbonate chips produced by sponge boring, spicules, and preserved endolithic sponge body fossils all point to the presence of endolithic sponges in Lower Cambrian reef cavities.The oldest previously described endolithic sponges are Early Ordovician in age and the oldest previously known reef interior bioerosion is Middle Ordovician in age. The presence of endolithic sponges in reef cavities of the Forteau Formation therefore extends both the record of endolithic sponges and of reef interior bioerosion from the Ordovician to the upper Lower Cambrian.