Lunulites conica Defrance, 1823
Colonies are free-living (lunulitiform), in plan view circular, up to about 10 mm in diameter, and in profile dome shaped and up to 3 mm high. The underside is either concave or flat (as a result of secondary calcification), and comprises kenozooids arranged in radial sectors. Large pores, sometimes countersunk, are arranged one, two or three across the width of each kenozooid. In fractured specimens the kenozooids have a prismatic appearance.
Autozooids are rhombic to diamond shaped, small, slightly longer than wide, on average about 0.30-0.40 mm long by 0.30 mm wide (fide Lagaaij 1952, p. 45). Preservation is very poor in all examined material from the Crags but, according to Lagaaij (1952), the cryptocyst is slightly depressed, granular, and best developed proximally, and the opesia is small (0.15-0.18 mm long by 0.14 mm wide) and semicircular. Gymnocyst, spines and ovicells are all lacking.
Vibracula are arranged in radial rows between the larger autozooids. According to Lagaaij (1952), they have relatively large opesia and are constricted laterally by a pair of teeth.
The small, button-like colonies of this species from the Coralline Crag are invariably abraded and few zooidal details are preserved. Many colonies of Lunulites conica are flat-bottomed, which immediately distinguishes this species from Cupuladria cavernosa and Reussirella haidingeri, the two other lunulitiform species found in the Coralline Crag. In general, L. conica has a more robust construction than either of these two cupuladriid species.
Pliocene, Late Zanclean–Early Piacenzian, Coralline Crag Formation, Suffolk, UK.
Also recorded widely from the Miocene and Pliocene across Europe (see Lagaaij 1952, pp. 46-7).