Unknown Devonian Brachiopod

UPDATE: I originally posted this as a clam but Howard set me straight pointing out this is probably a brachiopod. After more research this appears to be an Athyris spiriferoides (Eaton). I used this picture to help with this identification: http://www.paleoportal.org/index.php?globalnav=fossil_gallery&sectionnav=detail&submission_id=1260&taxon_id=&state_id=&period_id=13&assemblage_id=&last_section=search This website shows a list of the species found in the limestone layers of my area: http://www.indiana.edu/~libgeol/reprints/campbell.html

Here is an unidentified brachiopod I found recently. On this particular trip, I found maybe six clam fossils at this Clark County, Indiana location. I could identify the others except this one which I originally thought was a clam. This profile is one I am pretty sure I have not seen before. It is Devonian Period and appears to be from the Beechwood Limestone. It might be a Grammysia gibbosa (aka Grammysoidea secunda). Finding pictures of some of these species is not easy!

Here is our caravan leaving the fossil collecting location. The clouds are really out!



The arrows point out an interesting feature on this fossil shell. Look at the ridge lines that protrude away from it. I am not sure if these were there and fossilized or material just eroded away to form these patterns.