If if graptolites are found in a place then that place used to be covered by water, then what are found in place to indicate a place used to be covered by water?

Answer choices:
- mussels
 - Sea urchins
 - Conifers
 - patch reefs
 - graptolites
 - loose dirt
 - cartilage
 - Sediment

 

     graptolites     