Preparing rocks for a newt tank

Ok guys so I was at the beach the other week and collected a lot of these nice salmon/pink colored rocks. They are quite porous, and you can see that some little creatures had made their home inside once as you can still see the skeletons of corals and barnacles in some holes. Also unfortunately when I got home and tested one of the rocks (should've done this at the beach!) with a bit of vinegar, the animal skeletons fizzed on contact with the vinegar. I don't think the main rock was reacting, but rather the coral and sand embedded in it.

Does this make the rocks completely unsuitable for aquarium use? I hear the danger is that it will raise PH, making the water toxic more easily as well as possibly reaching PH levels unsuitable for animal life. I left them in my small outdoor tub/pond and the fish seem unaffected, though I've yet to test the water. If I can use these rocks, what would be the best way to clean them? Or would a one month life in the tub make them suitable for use by now?

Boiling might be helpful, as it gets rid of pathogens and also loosens sand and dirt.

Without knowing what kind of rock it actually is, it's impossible to say if it will be safe or not. Porous volcanic rock is OK, but rock that is porous because it dissolves easily isn't OK.

Thanks jennewt! I heard that boiling rocks could be dangerous? As for the pH levels I'll leave one in a bucket and test the water's there

I believe boiling round river rocks poses a risk for them exploding...I've boiled many rocks and am yet to have that issue (although I haven't used many round ones).

If the rocks are porous and have moisture inside them then causing the rock to heat up will expand the moisture and yes...the rock could blow up. this also goes for any rock, especially one sitting in water, not just river rocks. be careful!