What material could this be?

I found a puff ball on my floor and realized it belongs to one of my plushies. I only found the one at the moment but the plushie is missing two, one on each hand. If I were to replace the second one, what specific material should it be so that it fits in perfectly? If it helps, the plushie is a Hatsune Miku Christmas 2021 plush. A provided link would be useful but not necessary. Thank you!