Tellins and/or Tellens are bivalve mollusks that are members of the Tellinidae Family. The shells vary in profile and can be oval, trigonal, or rounded rectangular in outline. The anterior end of the shells are rounded, and the posterior ends elongated or pointed. The shells are fairly flat, often with a curve or warp, when viewed from the side. Many Tellins have valves that are equivalve (similar in size and shape). They have an external ligament and two cardinal teeth in each valve. Some species have lateral teeth also. Sculpturing on the shell can vary, but is usually concentric. Tellins have long siphons and can bury deeply in soft substrate. They use their siphons to feed primarily on detritus that has settled on the surface of the substrate. In turn they are preyed upon by crabs, fish, predatory mollusks and shorebirds. Their shells are covered with a thin periostracum and the shells often have a polished appearance.

Tellins are found in all global oceans, from shallow to deep water. They are some of the more colorful and graceful of the bivalves. There are hundreds of species in the Tellinidae Family of which thirty-nine are found along the coastlines of the Baja Peninsula.