Peeling the onion each day both Aru n me wonder what's the black ⚫️ mark on it. On further checking saw a post by Dr.Tulasi Chala, Guntoor. Took a small piece n rubbed it on a slide covered it with cellophane tape. Hav a small workstation which makes it easy to view and click pics sharing the same here, the quality of the pics nay not be great, exploration mode on.