The colony is multiserial, forming an encrusting, unilamellar sheet. Early astogeny is unknown.
Autozooids are slender, large, about 0.60-0.70 mm long by 0.17-0.25 mm wide, and typically rhomboidal in outline shape. Most of the frontal surface is occupied by the opesia which is elliptical in shape. Gymnocyst is lacking and the cryptocyst is restricted to a very narrow, smooth wall sloping steeply inwards around the perimeter of the opesia. Spines are lacking. Ovicells have not been observed. Basal walls of the zooids are uncalcified, or perhaps were aragonitic and lost during fossilization.
Vicarious avicularia are very common, some but not all associated with row bifurcations. Often two or more avicularia follow one another in linear series. Most avicularia are large, about the same length as an autozooid or slightly shorter, but significantly narrower, and acuminate. The opesia is hemielliptical, longer than wide, its distal limit defined by the calcified pivotal bar which is deep and has a downward-sloping distal face. The rostrum is overall spearhead-shaped, constricted at its sides by infoldings of the lateral gymnocyst, and has the form of a gothic arch distally where a moderate palate is developed.
Only one specimen of this species is known, encrusting a terebratulid brachiopod, along with some other bryozoans (e.g. Cribrilina) which it overgrows. Unfortunately, the colony is infertile. The lack of ovicells, together with the simple morphology of the autozooids, which have no frontal walls or spines, means that very few morphological characters are available to assist in species identification or generic placement. The most striking features are the numerous large avicularia with distinctive spearhead shaped rostra. No other bryozoan species in the Crags possess avicularia with such a morphology.
Generic assignment of this species is problematical. The two main candidates are Copidozoum Harmer and Crassimarginatella Canu. One of the main points of distinction between these two genera is the ovicell: this has an uncalcified ectooecium in Copidozoum, exposing the entooecium, but a calcified ectooecium in Crassimarginatella. In the absence of ovicells, the acuminate avicularia of Busk’s species marginally favours its assignment to Copidozoum. Fertile material will be required to test this hypothesis and hence the species is only questionably assigned to Copidozoum. An alternative possibility is that the species was bimineralic and originally had autozooids with aragonitic frontal walls (and basal walls) lost by dissolution. If so, it may belong to any one of many cheilostome genera, both anascans and ascophorans.
Pliocene, Late Zanclean–Early Piacenzian, Coralline Crag Formation, Suffolk, UK.