More often in the struggle to prize this thing open I used to squash the insect or caterpillar inside. Many of these were sacrificed at the altar of my curiosity though I was never able to see the whole life cycle of the insect: how it got there, how it made this cocoon and who flew out of it eventually.
So when I found it again at Moni’s convent recently I was filled with joy, similar to finding a childhood toy in the attic. I went through the whole exercise of opening it but found nothing inside. So this lucky one took wings before it could meet me or its end. I took a few pics to share it here. So if any of you have any idea of what this thing is then please let me know.