Coquina is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically-sorted fragments of the shells of molluscs, trilobites, brachiopods, or other invertebrates
Mudstone is a fine-grained, dark gray sedimentary rock, which is formed from silt and clay and is similar to shale but has less laminations
From Concha (Latin)+ Coquina(Spanish) +conch(English)= Couquina (mid 19th century)
From the English mud and stone, from low German mudde and stainaz
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock