Strophomenida

Strophomenida is an extinct order of brachiopods that lived from the Early Ordovician to the Late Permian periods. These marine invertebrates are characterized by their coiled shells, which are typically subequally biconvex or unequally biconvex. The ventral valve (pedicle valve) usually has a large, open delthyrium, while the dorsal valve ( pełni valve) possesses a prominent notothyridium.

The shells of strophomenides often exhibit a distinctive punctate microstructure, meaning the shell material is perforated by tiny pores. Many strophomenides were epifaunal, attaching themselves to the seafloor or to other organisms. Some species, however, may have been semi-infaunal or free-lying. Their feeding strategy was likely filter-feeding, using their lophophore to capture suspended particles from the water.

Geographically, strophomenides were widespread, found in marine environments across the globe throughout their extensive evolutionary history. They are an important component of Paleozoic marine fossil assemblages and are used by paleontologists in biostratigraphy and paleoenvironmental reconstructions. Notable superfamilies within Strophomenida include Strophomenacea, Productacea, and Chonetoidea. The diversity of strophomenides peaked during the Devonian and Carboniferous periods before declining significantly in the Permian.