Summarize the following:
This can get a little messy (especially if there are children around), so lay down some newspapers, put away any objects you don't want to get gooey, and grab your essentials. You'll need:  A small natural object (shell, leaf, bone, etc.) Petroleum jelly Plaster of Paris Water Small disposable dish or Tupperware container (such as a margarine tub) Any object from nature works -- shells, leafs, and animal bones are all good choices. If you do choose a leaf, make sure it's not dry and crackly. It must also fit in your container!

Summary:
Gather your materials. Choose the object you want to make a fossil of.