biostrome
/ˈbʌɪəstrəʊm/Geology
noun
A deposit consisting of a bed or sheet (as opposed to a mound or domed structure) of the calcareous skeletal remains of sedentary organisms (shells, crinoids, corals, etc.).
Origin
1930s. From bio- + ancient Greek στρῶμα mattress, bed: compare quot. 1932.