It normally isn't that hard. The rock and fossil parts look very different. Go to anyplace where you are allowed to take fossil rocks and do it yourself. It isn't hard to visually see where the rock (limestone ends and the fossil starts. Any 3rd grader can do a reasonable job of separating rock from fossil. There are parks like that all over - most fossils are just another clam (or similar sea creature) of the same type experts have seen millions (billions?) of and so there is nothing interesting left to discover.
Note, do not let the above take away the work experts do. While a 8 year old can do it, those are the easy cases, and a few "hammer slips" don't matter. There is a level of detail that trained hands can do better. There are many types of rocks that can hold fossils, and not all are easy as limestone to work with (limestone is the majority though).
Note, do not let the above take away the work experts do. While a 8 year old can do it, those are the easy cases, and a few "hammer slips" don't matter. There is a level of detail that trained hands can do better. There are many types of rocks that can hold fossils, and not all are easy as limestone to work with (limestone is the majority though).