Is this a spiny sea urchin?

[bigdogeder]

I have two of these that have mysteriously appeared in my reef tank. I am guessing they were hitchhikers on my live rock. Are they spiny sea urchins or something like that and are they reef safe? Thanks for the help

 

[johnmaloney]

that is a rock boring urchin. E. lu****er Can scratch acrylic, be careful handling them, those spines are sharp and brittle.

edit - the name is Echinometra lucanter, except the "a" in the word "luncater" should be a "u"

 

[bigdogeder]

Ok so I afoul remove them From the tank then?

 

[kay-bee19]

They're relatively harmless and tend to feed on coraline algae it finds on rocks and elsewhere in the tank.

Like many other urchins, when they get larger they be capable of moving or knocking over corals that aren't firmly affixed. I had hitch hiker rock boring sea urchin which was about the size of a plain m&m candy and grew to about the size of a golf ball before I removed it (because it was knocking over stuff).