How about a circle around which part you're trying to identify?
What engine? Doesn't look like a 4.0 so my SWAG would be the timing belt cover.
Edit - wait a sec...that's under the passenger footwell. I think that's the airbag controller on the left? Maybe someone hacked in a hole to replace the heater core or ac evaporator like you said. Probably easier to pull the dash then use that hole.
-Mac