Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
a A pine pollen grain, (b) a spirulina blue-green algae, and (c) a silicate diatom shell. The scale bars are indicated, and the parameters for the scans are given in Table 1. The colour scale ranges from 0 (black) to the maximum (white) projected density given in Table 1
