Coral Calcium Supplements

Has anyone actually tried this stuff? Is it legit better than your standard calcium supplement?
And more importantly, is there any downside to taking it?

I dug up a few links regarding coral-based calcium here:

http://www.korak-zdravlja.com/coralcare.asp

No. That’s total nonsense. Corals are basically just calcium carbonate—the same stuff you find in a lot of the mountains here in the US, gravel, and all that limescale buildup you find on a Toilet Bowl.

Calcium carbonate. CaCO3
Regardless of the specific biological structure (since there are polymorphs—basically different ways ions stack together in a mineral's crystal lattice), once it hits the hydrochloric acid in your stomach, you're left with Ca2+ ions. They are all identical. Whether you swallow limescale from a Toilet Bowl (ignoring the fact that it's crawling with bacteria), some gravel, or old limestone, the physiological result is exactly the same.

The CO32- ions within it reduce the acidity in your stomach, which is why it's used as a mild antacid. That’s the whole story. This whole coral thing is a complete scam. What's more, where they "harvest" it (while absolutely wrecking coral ecosystems in the process), there's significant heavy metal pollution in the area.

It's a scam, but a highly profitable one. Selling 50 grams of something that is fundamentally no different from gravel for $47... I have to hand it to them.
I see they're even selling "coral water" enriched with ionized calcium. Give me a break. 😁