joy13, Some have been known to scrape so hard against the silicon they can cause a tank to leak
Anyone have any experience to back up
I have urchins in my tanks, I think they're neat. I'd avoid the black spiny urchin, it quickly grows large and those spikes hurt. The collector urchin can be a pain because it'll pick things up and move them. I like them myself, just another neat thing to watch in the tank