A cut & polished ammonite from Madagascar. This one has warm brown calcite filling its chambers. The specimen is discreetly and permanently attached to a white plastic base.
Ammonites are extinct relatives of modern day nautiloids and squid. The largest known ammonite in the world would have been 8 1/2 feet (2.59 metres) across if it were complete.
Just under 3/4 inch (1.9 cm) wide, 5/16 inch (0.8 cm) deep and 5/8 inch (1.6 cm) tall.