They are relatively reef safe...I've had one before and never had a problem. Some folks have mentioed them eating corals...but since you got it already, just keep an eye on it...not like it is going to eat your corals over night. The biggest downside for me was having it knock frags over. But no worse than a large turbo snail.
I kept 2 for the longest time and never had an issue with them touching corals and they did a good job of keeping algae at bay. I second the fact they they can be bulldozers but if everything is secure then they are pretty cool little critters!
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