Icy ink. This tardigrade is sporting what is perhaps the world’s tiniest ‘tattoo’. Researchers used an electron beam to etch the dots into a layer of ice coating the animal. The beam transforms the substance into a compound that sticks to the tardigrade’s skin, leaving the design visible when the rest of the ice evaporates. The method’s extremely high precision means it could have applications in biomedical engineering, the scientists who developed the technique say. They are now working on tattooing even smaller organisms, including bacteria, in the same way.
Adapted from Z. Yang et al. Nano Lett. 15, 6168–6175 (2025)