The making of replicas of the original fossils, is pretty much the say way, just different materials, in which the fossils originally have been formed and preserved.
When an organism dies, be it a plant or an animal, it gets fossilized only if very quickly after the death it is covered with sediments or mud. The sediments or the mud protect the plant or animal from the outside influences, so once it is kind of in a vacuum, or protective layer if you will, in which parts of the plant or animal that are long-lasting are preserved.
The clay and plaster used for the replica, work in the same way, because they wrap around the fossil tightly and isolate it from outside influences, with the result being different though, as they just make a copy of the fossil.
Semipermeable means only certain substances can pass through. I imagine you are talking about cell membranes which are semipermeable. This means vital things like oxygen and nutrients are able to pass through the membrane, while not allowing everything to enter the cell
The disease caused by this is known as <span>C. difficile colitis, and it is life threatening. So I would prescribe different based on patient. If they are already at late stages of infection I would prescribe penicillin if they are in earlier stages any type one antibiotic would do</span>