Fossil beads are interesting looking and fun to make. I have made them both with pordelain clay and with polymer clay and like one as well as the other.
With polymer clay:
1. choose a neutral colored clay off white, beige, even flesh or a combination of scrap clay that will give you a light neutral color, and condition well.
2. roll out to about 1/4" thickness.
3.Use natural items as texture plates. (sea shells, coral, bark, pine cones (cleaned), weed seed heads, thistle heads etc.)
4. impress clay with texture items.
5. tear clay into shapes about 1" x 2" or "2" or the size you want or your texture field suggests.
6. make one or two hanging hole with a skewer or piercing tool.
7. Bake at 265 for 30 minutes in a clay dedicated oven or in a baking bag (those kind made for turkeys)
When finished baking and cooled it is time to tome them with pastel acrylic washes. When this is dry, brush surface with Pearlex. I like these left mat, but if you prefer a shine, coat with Future floor finish.
These look fine on a ribbon or cord, or use one as a a focal bead in a free form peyote necklace!