My partner and i were on oval beach watching the sunset over lake michigan. the sun was still relatively high in the air, but starting to get very golden and able to look at with sunglasses on. we both spotted a black cube/rectangle that seems to be rotating with the sun, very slowly to the left, from our viewpoint. it took up almost the entire left lower quadrant of the sun. i thought maybe it was a sunspot. my partner and i watched until it seemed to slowly rotate behind the sun and disappear. everyone else on the beach was involved in their own stuff and no one else saw it but us. it was not an aircraft. i searched for sun anomalies in the news, ufo sightings, nothing. the black of the object almost appeared to have a natural movement to the dark colors, almost amorphous) even though it was black and only barely moving until it disappeared behind the sun. ive never seen a ufo and my partner is a huge skeptic. 5 days later i saw a floating orb 10 feet from me that he could not see. i still can't believe this happened, hence my waiting in reporting it.