Wondering if anyone else had thrown Fava bean shells in the worm bin.

I had thrown some Fava bean shells in my worm bin. Almost after a month, shells still look as fresh as the day I threw them in. Worms are not at all interested in it as I could not find any shell that worms have attempted to eat. There are little black decomposing spots inside of shell, but outside still looks fresh green.

I had thrown green pea shells at the same time and they have disappeared.

Should I leave the fava shells inside the bin or pull it out?