You are presented with the question "the bones of what can be found to signify that place used to be covered by water?" and the following answer choices: 
- h2o
 - living things
 - dogs
 - adult sea squirts
 - bullfrogs
 - humans
 - an amoebae
 - gastropod shells

Now knowing that 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, choose the best answer.


 

        gastropod shells 