Which term describes sediment of biological origin formed from the accumulation of organic remains such as shells?

• A. Authigenic Sediment
• B. Biogenous Sediment
• C. Calcareous ooze
• D. Clay

Answer: (B)

Biogenous sediment describes sediment of biological origin formed from the accumulation of organic remains such as shells. It comes from the hard parts of organisms—calcium carbonate from shells and tests, or silica from diatoms and radiolarians—settling to the ocean floor over time. Calcareous ooze is a specific type of biogenous sediment that is mainly calcium carbonate; it’s a more particular case within the broader biogenous category. Authigenic sediment forms by chemical precipitation in place, not from organic remains, and clay is typically derived from weathered terrestrial material, not biological material. So the broad term that best fits the description is biogenous sediment.