Freshwater Rocks I Brought Home Rocks From A Beach In Florida That I Found, Are They Safe To Put In My Freshwater Fish Tank?

I brought home rocks from a beach in florida that i found, are they safe to put in my freshwater fish tank? - freshwater rocks

Stones ... This could be a kind of coral? i ound on the beach. I have already boiling, and now? Are they sure put in my tank of freshwater fish?