12cm. in circumference. Another one from the Wutach. Upper Aalenian. I found this one a long time ago before I knew any better and unfortunately almost destroyed the living chamber before I realized what I was doing. Haven't found any more of this species since then though, so it's still in the collection.
PS in Dec.2012. I've just changed the ID from S.discoidea to S.sehndensis. We've just discovered that this is only the second of its kind identified in the Wutach area.