DC Comics, for a time, advertised real KRYPTONITE ROCKS that you could send off money for, and receive a bunch of regular rocks covered in luminous green (possibly unsafe to breath near) paint. At least Kryptonite Rocks have a precedent. They're like the thing Superman hates! What is Space Ice. 3-D glowing substance. Well, 3-D isn't that impressive, since those are the dimensions all ice and most substances exist in. Not like anything you've seen before? So like...not ice? You can get it in three colours! But what is it.