Power Steering Pump
This power steering pump has a screw-on cap that incorporates a dip stick on the underside of the cap. The collection of dust on the top and sides of the pump housing suggests wicking of fluid from checking level and perhaps a little seepage. Nothing to be concerned about here because there are no leaks to be found. Keep in mind that on older vehicles, heat from the engine compartment can eventually deteriorate plastic components like these and cause them to develop leaks.