Skjellsandobservasjoner er et punktdatasett med over 3000 prøvepunkter, der skjellsand eller skjellgrus er påvist i bunnsedimentene. Skjellsand og skjellgrus er definert som sedimenter med over 50% kalsiumkarbonatinnhold.

Sampling stations where it is registered minimum 50% content of shell sand or shell gravel in the topmost layer of seabed sediments.

Shell sand occurrences show areas in the coastal zone with information about shell sand on the seabed, either based on mapping in the field or modeling. Sediments with a calcium carbonate content > 50% and consisting of whole or crushed calcerous shells are described as shell sand or shell gravel.