Florida Beaches Rock I.D. Please?

[NanaReefer]

A friend brought me some rock (she calls it coral) that I'd like to use in my tank. One of which would look awesome under my Sunset Monti.
Are they safe and what's the best way to clean them before adding them?

 

[ReelRednekReefer]

Having lived in Florida for 32 years and spending many a day in the gulf waters, those are typically the 2 types of rock you'll find out there. May find them on Atlantic side but I'm not sure. To larger ones look like calcium carbonate rock and would likely be porous enough to be good live rock, ID imagine if you look close you'll find small shells and such in the rock.

The smaller ones look more dense and are less likely to be calcium based, but I'm not sure. If it were my tank I'd acid wash the bigger ones then rinse twice with RO water, then soak in RO water for a week before putting in the tank. The smaller rocks would be nice in a FW tank...

 

[NanaReefer]

Thank you! It's the two larger ones I'm more interested in. Especially the top one. I can visualize the Monti totally encrusted on it [emoji7]