Hi, James,
Sorry for our delay in responding to your submission. I have been assigned your inquiry today and hope I can help.

Calcareous Tufa Calcite with Petrified Wood or Possible Bone Enveloped
Age: A few thousand years to tens of thousands of years
Source: Believed to be from North America; Southwestern United States; New Mexico

This is a variety of the mineral calcite. Deposited from water such as lakes and springs it is found across the plant. It has a porous structure and often contains fragments of leaves, twigs, and other forest floor materials. It is a relatively new rock formation on the Geologic time frame and had a Mohs Hardness rating of three. It is often formed in caves and along the runoff from thermal, hot, springs; as these sources bring the mineral from deep in the ground toward the earth's surface.
Example measures: 10'' x 8''x 5'' ; weight not given

Your example does appear to have a portion of an bone or tree branch. From images it is difficult to discern the material. I do suggest an in-person valuation to discover what your example contains. A regional geology department of a museum or University will be able to help. Another resource could be a rock and mineral show, or the reference desk at your local library. They may guide you to free resources. A regional auction house is another option, but they may charge a fee. Send my write up and the images you have given as an introduction. An increase in FMV if the encased item is a bone; the lesser price for a petrified wood example.

For more information on calcite please refer to:
https://geology.com/minerals/calcite.shtml
More in-depth information on the importance in research of such examples: https://www.sciencedirect.com/science/article/abs/pii/S0305440314002581