If fossils of a water animal or plant are found in a place then that place used to be covered by water in the past, and gastropod Shells of marine animals are often preserved as fossils. Given these facts, the bones of what can be found to signify that place used to be covered by water among the following options:
- h2o
 - living things
 - dogs
 - adult sea squirts
 - bullfrogs
 - humans
 - an amoebae
 - gastropod shells


 

        gastropod shells 