Radiolarians are protozoa – one-celled animals with a nucleus – that make the most remarkable skeletons. They're free-living ocean plankton, unbound by gravity, and their glassy shells vary wildly from simple cups to intricate polyhedral fantasies. They've been observed with interest and wonder since the invention of microscopy, most famously by Ernst Haeckel in the remarkable of illustrations of Kunstformen der Natur. But until now we've seen them only in 2D – these models are the first 3D scans, and they are all that we hoped.

These radiolarian tests were collected near Barbados, from sediment dating from the Tertiary period. More about them and the imaging process, with many gorgeous photos, is here. I encountered this data in this Microscopy Today paper by Roger Wagner et al. Dr. Wagner kindly shared the models for this project.  The X-ray tomography scans were done by Denis Van Loo of XRE Engineering.

Radiolarian skeletons are themselves siliceous and translucent (in some places they're common in sand), so except for a scale factor of about 300, this model is quite true to life.

Taxonomy

Which species? Exact identification of these organisms isn't easy: there are a lot of them and taxonomy is, to quote Dr. Wagner, "muddled". These are tentative identifications, if you know better we'd be pleased to hear from you:

	Acrosphaera trepanata	Haeckel 1887
	Heliodiscus echiniscus	Haeckel 1887
	Stylatractus cronos	Haeckel 1887
	Actinomma popofskii	Petrushevskaya 1967
	Anthocyrtidium ophirense	Ehrenberg 1872
	Ceratospyris hyperborea	Jørgensen 1905

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