Whats wrong with my gerbils eye?

He has a little lump under his eye?

heres a picture of it -


i actually have no clue, i looked it up on the internent and found nothing.

it looks kinda like theres a bump in the vessel so maybe its a cyst. it seems harmless though assuming it can see and the lump isnt sore. just monitor him and make sure its not changing size or color