I found this at a house I am flipping. It is located on a hilltop of the desert with a wash on either side descending to a riverbed. There is a quarry along the riverbed where I get stone for landscaping, That stone is jagged and is colored orange-rust and white. This egg-shaped rock or specimen, however, is perfectly smooth with gray and plum coloration with a distinctive dark pattern and light spots. It is approximately 6 inches long. What do you think?