Odd color, perfect posterior

Found a perfect Meg posterior, all serations, actually pulled it from some sandy blue clay. the tooth itself is a creamy white root, and tan/grey enamel. I found two inch-long makos in the same stuff, but both were dark grey root, black enamel. Anybody know why this'un was almost white? it was completely surrounded by matrix except a tiny bit of the root lobe, and about 3 milllimeters worth of serrations/enamel. But i've never pulled a tooth this color from that kind of matrix. Never seen any teeth with even a remotely similar color come out of that stuff.

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