This dataset contains cell measurements (length, width and wall thickness) for an unidentified coralline alga of the genus Sporolithon, labelled Sporolithon sp1. Samples were extracted from limestone collected in 2015 and 2020 in Meghalaya, NE India (Eastern Tethys), corresponding to a time before and during the Palaeocene-Eocene Thermal Maximum, PETM (~55.8 Ma).

Samples were prepared into thin sections, images were taken using a Hitachi S-3500N variable pressure scanning electron microscope and then measurements made on images using imageJ.