cave pearl

cave pearl

[′kāv ‚pərl]
(geology)
A small, smooth, rounded concretion of calcite or aragonite, formed by concentric precipitation about a nucleus and usually found in limestone caves.
References in periodicals archive ?
Other speleothems include flowstone that looks like a rock river, rounded polished cave pearls, and feathery aragonite.
Just like the pearls that oysters make, cave pearls are made of -- formed around a nucleus of --.
Others are called fried eggs, popcorn, cave pearls, and soda straws, because that's just what they look like