Diagnosis

Calcareous nannofossils are characterised by cuboid or stellate shapes, which likely represent holococcoliths composed of hexagonal prisms. The crystals are frequently arranged into distinctive swastika-like or cobbler’s anvil-shaped blocks, often featuring a prominent central cross.

Remarks

Optical Properties: All members of the Miculaceae family display parallel (straight) extinction. Bowmania exhibits length-slow (+) elongation, while Micula shows length-fast (-) elongation.

References

Varol, O. 2025a. A practical guide to optical studies of calcareous nannofossils. Grzybowski Foundation Special Publication. 29: 1-222