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.