Brachiospongia digitata By Matt Young October 30, 2017 11:00 MST Photograph by Dan Phelps. Photography contest, Finalist. Brachiospongia digitata – fossil sponge. Mr. Phelps writes, "I recently excavated this specimen of B. digitata from the Curdsville Formation of the Lexington Group (Late Ordovician). I had intended on carefully excavating the layer in the future, but this specimen was in fragments at the surface. I glued it back together then removed a lot of the excess shale from between the 'arms.' The specimen could use more cleaning."