Supraorbital Gland
The supraorbital gland is a type of nasal gland that is found in penguins. The supraorbital gland converts saltwater to freshwater, which is the reason why penguins are able to drink saltwater. It operates similar to how a kidney works.
The word "supraorbital" is in reference to the area just above the eye socket (orbit, orbital bone). Living in saltwater environments would obviously pose a problem for penguins because drinking so much saltwater would be very unhealthy.
The supraorbital gland has water-filtering capability. Saltwater often enters a penguins system by way of the prey that they hunt, and excess saltwater is bad for a penguin. This is what the supraorbital gland is for. The gland surrounds a capillary in the head, and is located just above the penguins eyes. The capillary that it surrounds is continuously filtering out the salt from the saltwater that a penguin ingests.
So what happens to the salt? The penguin loses the salt in the form of a brine substance through its beak/bill/nose. Sometimes this fluid drips out and make it look like the penguin has a runny nose. It also causes the penguins to sneeze it out sometimes.
When penguins are living in captivity and aren't around saltwater, like in some zoos, they don't need the suborbital gland, so it isn't used because it has no other function. However, having a non-working supraorbital gland does not negatively affect the health of a penguin, as long as it doesn't ingest a lot of saltwater.