I have absolutely no idea! It looks like a sauce of some kind... I would throw it out, but I hate doing that with other peoples stuff. Fairly sure half the freezer is forgotten stuff too!
Also, I live with my landlord who tends to hoard stuff.. Apparently he went gluten and dairy free, and gave me a jar of pesto with Parmesan he couldn't use... I looked at the date and it was from 2012 xD
We bought a new fridge recently and our previous fridge was really small.
I caught my bparental angrily muttering to himself last night, "Before, not enough space, everybody fights. Now too much space! So empty! I don't know whether or not someone has eaten my food because this fridge is so big."