Dear Daniel,

Thank you for contacting Mearto with your appraisal inquiry. My sincere apologies for the delay with the apprisal.

The presented object appears to be unidentified fossilization with the measurements of 2 inches height, length, and depth. Embedded in a stone material we see round structures as we know it from haulms and some layered structures which remind us of the many layered shell structures of oysters. This could be a part of a conglomerate of a fossilized oyster and parts of fossil crinoids.
A fair market estimation would be between 2 to 5 USD.
This estimate is based on actual recent past recorded auction sales of comparable items. Retail "asking prices" can be higher and may vary.

With kind regards,
George