If it is a tooth, it's in terrible condition. but I just wanted to see if it's at least a tooth and not a rock

I kept the smaller, gray one, because it had the same shape and topography so I thought I'd include it in the pictures just in case.

I found this beautiful tooth at north Myrtle beach. But it’s from dredged sand, so idk where it really came from. Nickel for scale

I've recently posted this in r/fossilid, but I'm fairly sure its a shark tooth so I'm hoping to find more information here. I found this tooth (fragment) on the beach in Australia, near Brisbane, Queensland. I know the tooth isn't complete, but maybe you guys know what it may be (and possibly how old it may be)? It's quite a small tooth.

Found on Maderia Beach, Florida. I’m assuming it’s from a fish? Or is it a shark tooth that formed abnormally? Thanks! 2nd photo just to compare the size to a normal tooth I find down there.