The dye alizarin

Alizarin is a red dye that can be extracted from the roots of the plant Lady's bedstraw Galium verum. You can see the plant in flower as an extra.

I first came across the dye in my undergraduate histology classes where it was used to stain calcium deposits red in biological preparations.

The main photograph shows the skeleton of a bat that has been stained with alizarin and then embedded in perspex. It is striking that the bat skeleton contains the same bones as does our own, albeit in very different relative sizes!