"Pszemol" wrote in message ...
"Yukon" wrote in message ...
I had a pincushion drag around a snail shell with
a mushroom on it for months. I also have had them
strip insulation right off the wire of a powerhead and
fry a tank. It was only a 10 gallon tank, but it could've
happened in any tank. I still have urchins in all my tanks,
but I keep an eye on 'em.

Dont you have problems with pincusion urchins drilling
into the rocks? I have read somewhere that the only
reef-safe urchin is blue tuxedo urchin (Mespilia globulus)
but other urchins is like all bets are off...

How one can recognise rock drilling urchin from
a reef-safe algae eater ?

All my pincushions have ever done is strip algae (all kinds), and wire insulation.