These bumpy ammonites are from Madagascar. They are between 65 to 135 million years old. These brown and gold coloured ammonites come in a variety of sizes, from very small pieces which are suitable for jewellery to very large pieces, some as big as 60 cm (2 feet) across.
The “golden colors” are actually barite and calcite mineral replacements on the original fossil specimen, caused over millions of years of the fossil process. When polished on the outside, often suture and growth lines cover the ammonite. This of course makes the ammonite extremely beautiful, which makes it more sought after, as well as more valuable and rare.