"Pszemol" wrote in message ...
"Yukon" wrote in message ...
All my pincushions have ever done is strip algae (all kinds),
and wire insulation.

Wire insulation??? That sounds scarry...
What devices they chew on?

I've had pincushions in all my tanks for over 15 years, and it only
happened once. The urchin stripped a small spot on a heater cord down
to the bare wire and fried itself and a dwarf lionfish in a 30 gal tank. It
was a new heater too. So I always check my powerhead wires too.