For a calcareous ooze to exist below the CCD, the following requirements must be fulfilled:
1. The calcite shells must be deposited above the CCD.
2. The shells must be covered by a non calcareous material.
3. The movement of the sea floor over a long period of time.
CCD stands for Calcite Compensation Depth and it is the ocean depth below which calcite is unstable and will dissolve quickly.