starting this off with a TRIPLE FACEPALM, what i decided to do was restore my trilobite fossil with some tweezers, un-chlorinated water, and a paintbrush. i discovered something on the front of the trilobite that i had previously thought to be a part of the trilobite, turned out to be compacted dirt. i chiselled it off, and went to do the same thing to the other side of the trilobite, except there there had been mud on one side, there was stone on the other. can anyone help? i don't intend to repair it (too damaged) and i just want to know what went wrong, why it was like that, so on. here is a picture.
flip it so it is right way up if you can. then: the left side is the side adjacent to where i removed the compacted dirt, however it has rock where the other has dirt. the right side is where i removed the dirt.
I can only compare the fossilisation that your trilobite has endured with some fossils that I find on the Holderness coast.
Most of the time ammonites that I find are not preserved exactly the same as the one next to it in a multi block death assemblance, infact a single ammonite is much the same as the preservation on your trilobite were you find the removal of rock hard in one area but easy to remove on the other side.
Fossil bone is a good example were you can usually remove the surface of the matrix next to and arround the bone using mechanical means, but then you have to revert to chemicals because of the high pyrite content in the rock.