Hmm, perhaps, my thoughts were of electricity because it was suggested to me that the build up may be caused by that. Their jerking movements also led
me to believe that as well. To be on the safe side, I'm replacing the heater (which was old/used and some generic brand when I got it). I'm sure it could be the heat as well. I'd like to know if anyone else has seen this kind of behavior around their heaters?