Is this rock safe for a reef tank

[Sigma2]

I got this rock from a beach (Florida) and I was wondering whether or not it would be safe to add to a reef tank and if so how to clean/prepare it. (Sorry for the low quality pictures.

 

[Subsea]

Looks like dense limestone. Perfectly acceptable to use in a reef tank.

Is you tank already set up?

 

[blecki]

If it's been out of water long enough to dry out, you really don't have to do anything to it but maybe rinse off any crud and give it a good shake.

If it's still wet it depends on whether you want to sterilize it first or not.

If it's really crusty (looks pretty clean in the picture) an acid bath might be in order.