Each fish has preferences, okay. Im watching my fox nibble the spines on my long spine urchin. I mean I've watched this fish nibble just about everything in the tank at least once, but this behavior is peculiar. There are currently 3 macro stashes and the daily seaweed has been eaten so this fish is not under fed by any means. I've seen the fox pop the broken spines up from the gravel and eat it like a carrot and I have seen the fox nibble the spines on the urchin. Its not aggressive or mean. Is this as odd as it seems to me? Good source of calcium?