Earliest encrusting calcareous Foraminifera from the Sheinwoodian (lower Silurian) of Saaremaa Island, Estonia

The world's oldest encrusting calcareous Foraminifera are here described from the Sheinwoodian of Saaremaa Island, Estonia. The encrusting Foraminifera represents a new species of the genus Earlandia, and E. giga n.sp. is characterized by a slightly conical and huge bilocular test. The foraminifera encrust gastropod shells in a gregarious manner. The Estonian material suggests that early calcareous Foraminifera had already experimented with a range of life strategies, including large body size and attachment to hard substrates. Our findings challenge the traditional narrative of early calcareous Foraminifera as exclusively soft-substrate dwellers, indicating a more complex ecological differentiation during the early Palaeozoic.