There is considerable variation in rhodolith morphologies within the study area. At Site 1, the rhodoliths are dominantly spherical to discoidal in shape and less commonly elongate. Sizes range from between 4 to 10 cm long and averages approximately 6 cm. Coralline algae is mostly laminar although small stubby, ( 1 cm high) columnar growth form is also present. Secondary encrusters include foraminifera (Homotrema), gastropods and serpulid worms. Macroborings are also common across the surface.

Rhodoliths at Site 2 are mostly ameboidal to elongate in shape. Average rhodolith size is 8 cm long, but may be as long as 13 cm. Coralline algae is mostly columnar (average 1 cm high) with minor laminar form, giving an overall bulbous appearance to the nodules. Secondary encrusters include encrusting foraminifera (mainly Homotrema), serpulid worms, gastropods and locally developed juvenile Montastreas. Borings are common but typically less abundant than at Site 1. Nevertheless, the overall porosity of these nodules is greater du to the columnar structure of the coralline algae. Centimetre scale void spaces are commonly infilled with early lithified bioclastic sediment. Encrusting gastropods are also locally present within the cavities.