Marble is a very hard rock that's a particular type of limestone. Fancy lobbies (and even bathrooms) are often lined with marble.
Marble's unique qualities make it a popular stone for artists and kitchen designers alike — the white stone statues you find in most museums, some of them dating back to ancient Greece and Rome, are carved from white marble. High-end kitchen counters are often made from polished slabs of darker colored marble. A single marble is a glass ball swirled with marble-like colors, and "to marble" is to paint with similar swirls and whorls.