Does anyone know what this white **** is for in the trunk space of the Volvo XC90? It is under the carpet and adjacent to the wheel jack tool to the left of the battery compartment. It is a **** that can be tightened close or left open. What is it for? What is it called? Can I leave it closed?

 

Is that simply a protective plastic cover over an exposed stud? Un screw it and see what happens.

 

Thanks, yes it is a plastic protective cover for the threaded side of a bolt. Which brings up the question, what is that bolt for? The head of that bolt is underneath on the underside of the trunk area and is not visible from the trunk area shown in the picture.