Do you mean the HDD 3 icon only?
If yes, then download & install the free Tweak UI click here.
Run it once installed & choose the last entry in the left panel, i.e. Repair & with 'Rebuild Icons' selected in the right panel, click on the 'Repair Now' button. Leave it for about 5 minutes, then I would recommending rebooting before checking to see if there's been a change for the better. G