Is coral safe for fry?

I've been keeping fish since Moses wore short pants. Well, that is, since I was a little tyke some 30+ years ago. I've never got into breeding, but I'm going to give it a whirl!

I bought a Marineland Silhouette (3 gallon) back in December, let it cycle, and added a male & female guppy. I know I should've had 2-3 females, but that's off topic here, lol. She was certainly pregnant and when I noticed her birthing I moved her into a breeding box. She had 17 fry (that I could count) and there are 9 still kicking

The male died, but from what I understand the females will retain enough sperm to have three litters. Sure enough, she's certainly pregnant again and the 28th day from her last brood will be this coming Sunday.

I already have a new tank setup & cycling. I put in API Stress Coat and Quick Start. The heater is set at 78 and I plan to move her over to that tank in the next day or so.

Long story short, here is my question. I went to the only local fish store in my small town today. It's been open since the 70's and the owner is awesome! I bought this beautiful piece of coral (6' x 4") for two bucks! My thought was it would give the fry plenty of holes to hide & play in. Though, now I'm wondering if this will be safe in a tank for fry because of the sharp edges all around? I certainly don't want to defeat the purpose of giving them a safe tank to be birthed in if they're only going to be hurt by this.

Make sure the coral hasn't been sealed/ painted with a clear lacquer and rinse it well before adding it to the tank.

Dead coral skeleton will raise the pH of the water but that shouldn't be an issue for livebearers like guppies.
You will get some gunk collect in the gaps and that will need to be sucked out with a gravel cleaner.
Over time the coral will get biofilm (bacterial slime) and algae on it and that will smooth the edges off.

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Female livebearers (guppies, platies, swordtails, mollies) can carry up to 6 sperm packets and they use 1 sperm packet per batch of eggs. Theoretically, female livebearers can produce young for up to 6 months after males have been removed.

If you want to breed livebearers, just keep a tank with females and let them give birth every month. Eventually when they run out of sperm packets and you have had no young for a few months, then add a male for a week before removing him, and the cycle will repeat itself. But wait a few months before adding a male and only leave him there for a week or so.

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Do not lift pregnant female fish out of water or you can damage the developing young. If you have to move a female, carefully catch her in a net but keep her in the water. Put a plastic container in the tank and fill it with tank water, then move it under the net and lift the female out in the net that is in water.

Try not to move females if they are heavily pregnant. Just leave her in the tank until she has given birth. Wait until a week after she has given birth and then move her.

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Have lots of plants in the tank and feed the female regularly and let her have babies. The best plant for livebearers is Water Sprite (Ceratopteris thalictroides/ cornuta). It is a floating plant but can also be grown in the substrate.

WOW! What an amazing & helpful reply. I appreciate all the information