Fossils are formed when layers of sediment cover the remains of organisms over time, and sand and mud are examples of sediments. Given these facts, what covers remains to create fossils among the following options:
- Sand and mud
 - Oxygen and water
 - Calcium carbonate
 - Volcanic ash
 - shells
 - some invertebrates
 - Water and oil
 - detritus


 

 Sand and mud        