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I've been showing some of my finds here from the Middle Jurassic Callovian stage in the Wutach valley recently and I've been busying myself today with this: You can see the mineralized inner whorls clearly and also a faint outline of the more outer whorls. It wasn't quite clear from the outset how much of this ammonite was hidden under the matrix, but there were at least a few indications as to where I could begin setting the airscribe, so I carefully chipped off a bit of matrix from the two blocks in order to get my bearings and then glued the two pieces together. You can now imagine roughly where the ammonite runs around, although I was starting to have my doubts about the preservation of the outer whorls, particularly on the right hand side. There are a lot of iron oolites in this particular matrix, which sometimes cause some heavy corrosion. But in order to find out, all I could do was to dig away a bit more and try to get down as close to the shell as possible. The next photos show front and back after this procedure. You can see a white streak at the bottom in the first photo, which indicates a bit of shell from an outer whorl showing how large, or maybe even larger it may have been, but that has long since been a victim of corrosion. Now it was time to get down to some serious abrading in order to see what kind of condition the shell was in. The matrix is a relatively friable iron rich marly limestone, so it gives way quite easily. I know that the shells at this exposure can take up to 80psi, but just to be on the safe side I started with 60. At this point it became obvious that the outer whorl from 9 to 3 o'clock was too corroded to be of any use, so there remained no other choice than to remove that part. Front and back views follow again. Now that I knew what could be made of it, it was time to abrade the rest of the matrix off the shell. I wasn't quite finished with the back as I took the next photos. Here it is after the finishing touches; abrading the inner whorls on the back, smoothing up the block with air pen and abrader and finally applying a thin coat of beeswax finish. A Homeoplanulites sp. with a diameter of 7cm.