| A tangle of tabulate corals from the Middle Silurian section of the Lower Silurian to Lower Devonian Vaughn Gulch Limestone, Inyo County, California; called scientifically Coenites (an older reference for this same genus is Cladopora sp.). Specimens are silicified--that is, replaced by the mineral silicon dioxide; reddish-brown coloration derives from the mineral limonite, a variety of hydrated iron oxide. Photograph taken by an individual named Scott Blair, who etched the specimens to such attractive relief on the limestone matrix with dilute acetic acid. I processed the image through photoshop. |