I may pick up some more and airbrush them this time around, instead of dying. I figured that, being sponges, they would have taken the color throughout by absorbing the paint. Instead, the core of each sponge reverted almost entirely to its original color and the extremities grew algae or mold.
Someone else suggested soaking them in diluted pva first.
Due to being like a aero-bar full of air they can be quite light, some lava rock can float in water. Depends on how much steam they get in their creation: becomes the equivalent of frozen foam. I just look for the ones with the most holes: looks like a crater filled asteroid.
A revolution is an idea which has found its bayonets. Napoleon Bonaparte