Eiffellithales

The order Eiffellithales, comprising loxolith/discolith calcareous nannofossils, is characterised by the presence of single or double walls. These nannofossils possess central structures, such as axial or diagonal crosses or bars, which may or may not support a distal process. The outer wall exhibits constant extinction under cross-polarised light (XPL) and consists of:

• Sinistrally imbricated segments, as seen in the suborder Eiffellithineae,
• Protolith segments, as observed in the suborder Stephanolithionineae
or
• Dextrally imbricated segments, as found in the suborder Zygodiscineae.

The inner wall may be imbricated, protolith, or tangential, often displaying interference colours.

Rood, A. P., Hay, W. W. & Barnard, T. 1971. Electron Microscope Studies of Oxford Clay Coccoliths. Eclogae Geologicae Helvetiae. 64: 245-272.