Pilots usually assume a wind sock will be available to indicate wind direction and intensity at every airport. Occasionally though, a different type of wind indicator will be utilized by the airport, though this is extremely rare.
A real-life tetrahedron in the wild at the Buckingham Airpark (FL59).
How rare? It’s so rare that I literally stopped and took a picture of a tetrahedron not all that long ago when I saw it at an airport I was passing by.
An alternative to a windsock, the tetrahedron points into the wind. It’s literally a triangle/pyramid on it’s side and will swing with the wind, pointing into the wind, essentially like a weather vane on an old barns a country farm.
The tetrahedron is rare, but they are still utilized so a good pilot will be able to recognize them and understand the information they are displaying. Again, as a wind blows, the tetrahedron will shift, pointing into the wind, showing pilots which way they should takeoff and land (which is done, of course, into the wind).
It’s also important to understand that a tetrahedron operates/indicates opposite from a wind sock, so it is important not to confuse the indication. A wind sock is inflated by the wind and points with the wind, whereas a tetrahedron will point into the wind!
-Fly Safe, @MTElia1B9
Review Before Flight 
Interesting – whereas a windsock also provides wind strength, i cant see how this would do that also?
That is a great point… Thank you for pointing it out. A windsock has the ability to illustrate the intensity of the wind, whereas a tetrahedron can only show the wind direction.
It’s also important to remember that sometimes an airport will lock the tetrahedron to show the preferred runway. If this is done, it won’t swivel as the wind shifts, so you should still listen to the ASOS/AWOS.
I was unaware of this until I took an AOPA Air Safety course, recently.
Great point Tom! Those AOPA Air Safety courses are a fantastic resource.