The first work was done by pouring small amounts of vinegar on a 12"x8" (30x20cm) block of Moroccan Devonian(?) limestone containing crinoids. While the acid worked the block was constantly being brushed. This kept the acid from sitting on the higher, already exposed portions of the fossils. Action was concentrated on the lower pockets of softer limestone. The roughing action of the brush speeded the action of the acids on this softer material. At the start there was only a hint of the larger crinoid but now three are exposed on the slab. When the supply of vinegar (acetic acid) was exhausted, a 1% solution of muriatic acid was used with about the same results.