Brachiopoda: Latest Proterozoic to recent. Bivalves, but not clams, with shells that are inequivalved and bilaterally symmetrical. Filter-feeders, shells were suspended on a fleshy stalk called a pedicle. Two classes, Inarticulata, Articulata. Important guide fossils from Ord.-Perm., then declined. 10,000-30,000 fossil species, about 300 species today. Articulate brachiopods have toothed hinges and simple opening and closing muscles, while inarticulate brachiopods have untoothed hinges and a more complex system of muscles used to keep the two valves aligned. The "fossil" in the picture below is a living species called lingula. Does it seem to be an articulate or inarticulate brachiopod? What name is given the fleshy 'stalk' at the top of the picture?.