Strophomenida

The Strophomenida were an order of extinct brachiopods, commonly known as lamp shells, that lived from the mid-Ordovician to the Early Jurassic periods. These marine invertebrates are characterized by shells composed of two dissimilar valves: one strongly convex and the other concave. A notable feature of their shells is a laminated pattern along the margins, accompanied by fine, bowlike growth lines.123

Brachiopods, in general, were once among the most abundant life forms, though they are less numerous today. They are found in all oceans and are distinguished by their two-part shells, which resemble ancient Roman oil lamps. The Strophomenida are considered representative of an important group within fossil brachiopods.13