Some of the links on this forum allow SMF, at no cost to you, to earn a small commission when you click through and make a purchase. Let me know if you have any questions about this.
A picture against a solid background rather than the stone counter top would be easier to see, but it looks like part of the meat to me. Like Inda said, if it was mold it would wash off to some degree.
Thanks all. Don’t think it’s mold. Likely seasoning deposits or fat. Meat was eye of round. Was only in a few pieces so I’m chalking it up to something unique and not worrying about it. Just had never seen it before on other batches. This was the first time I’d trimmed my own eye of round so I’m leaning toward it being some fat didn’t get trimmed well enough.