I have found the same thing a few purchase plan over the years. It's not perlite and it's not fertilizer pellets. The ones I found look like a tiny little brain, or an engorged tick body. Some are dried and have been opened to let something out, or hatch. I think mine were some type of spider egg. The outside is kind of slimy and a little translucent. And little tiny specks come out with fluid if you squeeze it. I would love to verify if it is spider eggs. I have also found lizard eggs in the past in a plant outside here and there. Good luck ID in yours.
