Stringy stuff in Purina Pro Plan dry cat food?(Pictures attached)

When giving my cat more food tonight I noticed some strange stringy stuff mixed in with his food in his bowl. I picked it out and noticed it har a mucus-ish texture. To be safe, I dumped the bowl and went to pour him more from the bag we’ve been using (closed with a big clip). After pouring I noticed far more of this stuff in the food. For context my cat has already eaten through about half of this huge bag of food over the last month or so, so if it’s been there this whole time I haven’t noticed and it hasn’t really bothered him. Does anyone know what this is and if it’s dangerous for him? Needless to say I will not be giving him food from this bag anymore.

Pictures are attached if anyone can help with identification.