Introduction
Hi! You wanted to know more about Crystal Prisons? Well, fortunately, I can help you with that! I'm Firn! I'm the official spokesdragon for the species (I like talking more than my siblings), and can tell you all about them, since I'm one myself!
Crystal prisons, are, as our name implies, prisons! You see, if you have too many shade fragments in one location, they attempt to recombine and become stronger...which isn't good if you're trying to store all the dangerous shade fragments in one location, like the fortress of ends. Which is where we come in! The Icewarden himself chose us to help with this by becoming portable prisons to keep the shade fragments safe and far apart from each other. He imbued us with his own ice to keep us from being affected by the shade, and allowed that gift to be passed down in our family lines!
Now there's 2 types of crystal prison: those with shade already, and those without! My brother Cirrus doesn't have shade, for an example. He's a collector- he's supposed to go out and collect any stray shade fragments and keep them safe, but he hasn't found any yet. I, on the other hand, do have shade. Mine is some of the original from the fortress of ends, that I took when my grandmother wanted to go serve there. Most of us store our shade inside us, where it's least likely to contact the outside world. I have heard stories of Crystal Prisons in the distant past, however, that weren't able to store the shade inside them, and instead stored in in special crystal growths along their flanks. While it's easier for the shade to escape, the spikes can help in defense against anyone that might be staging a 'prison break'.
Crystal prisons can be any species, but they do have to be ice element, unless they're so passionate about helping they've asked the Icewarden to grant them his ice anyway.