Fact 1: 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.

Fact 2: Barnacles are animals that live in the water.

Given the two facts above, answer the question "what fossils have to be found in a place to signify the place used to be covered by water?" with the following options: 
- bullfrogs
 - Sediment
 - Sea urchins
 - dinosaurs
 - barnacles
 - humans
 - patch reefs
 - natural gas


 

     barnacles    