2022 (P) Maya Angelou Quarter - Retained strike-through I regret selling

Found this coin roll hunting a while back. There's foreign debris caught between the die and planchet during striking, and it's still embedded in the surface through "UNITED STATES" and the top of the rays. This is one of my favorite strike-throughs I've ever pulled from a roll, and honestly one I regret letting go. I love when the devices are struck into the debris. I have my guesses, but what do you think the retained debris is?