Description - the following groups of Neogene nannofossils are thought to be related to coccolithophores, but produce structures which are neither heterococcoliths nor holococcoliths.

Braarudosphaeraceae	Ceratolithaceae	Discoasteraceae	Sphenolithaceae	Triquetrorhabdulaceae

The term nannolith has been used, especially by palaeontologists, as a convenient term for structures about the same size as coccoliths and occurring with coccoliths, but lacking definite coccolith affinities. In the modern nannoflora, there are fewer groups of cryptic origins, and the term has been less widely used. However, it is useful for calcareous structures that are thought to be formed by haptophytes, but probably by a different biomineralisation process to either heterococcoliths or holococcoliths (Young et al. 1999).

NB The first use of the term in this sense appears to have been by Haq (1978, in Introduction to Marine Micropaleontology), and this was followed by Perch-Nielsen (1985, in Plankton Stratigraphy). By contrast, Aubry (1988 et seq., Handbook of Calcareous Nannofossils) places most of these groups in the Ortholithae.