Hi. i can feel a small (pea sized) movable lump inside the belly fat at my left abdomen, just under my rib cage. what could it be?

Lipoma: Often times these are lipomas, which are simply benign masses of fatty tissue. Very rarely do these cause any problems - in rare cases, there may be persistent surrounding inflammation which leads a patient to ask for removal of the lipoma. As with any lesion, if there is significant increase in size, or significant pain, redness, discoloration, or any other concerning sign, do see a physician.

Most likely Lipoma: Which it means fatty tumor benign in type. Having said that every lump should observe.