Trioxane fuel tablet recrystalization

I had a bunch of old military trioxane fuel tablets. I decided to open all of the packets, maybe a dozen, and place the contents in an empty tin coffee can with a plastic lid. I put the can in a dark closet. I let it sit undisturbed for several months. Upon opening the can, I saw crystal structures growing off of the sides of the tin can. They appear to be of a lightweight somewhat flexible plastic composition and are flammable in the same way that the rest of the fuel is. If I disturb them by damaging them or removing them, more will grow over time, if I let the container sit. What is this reaction? Has anyone witnessed this before?




It's *[subliming](https://en.wikipedia.org/wiki/Sublimation_(phase_transition))* (aided in this case by decomposition) and re-depositing.


Substances that turn directly from solid to vapor (e.g. naphthalene, water ice) are said to *sublime*, rather than *evaporate*. The inverse, changing from vapor to solid, is termed *deposition*.


When water vapor deposits on very cold surfaces, such as "dry ice", it grows into amazing dendritic crystals:


[![water ice crystals on dry ice](https://i.stack.imgur.com/5h0iZ.png)](https://i.stack.imgur.com/5h0iZ.png)


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