The dots are also an excellent source of iron and calcium. If you're ever lost in the wilderness and in short supply of vitamins, you should be eating the livers of the animals you kill and gnawing on their bones. But if you can't catch any animals, or if your teeth are worn down too far already to gnaw the bones properly, you could do much worse than to pry loose a few of these "smurfs" and gobble them down.

The blue reflectors in the midst of the road are trapezoidal prisms; that is, an isosceles trapezoid projected along the axis normal to the trapezoid. The reflectors are not placed in the middle of the road; rather, they are placed offset to one side of the road.

Located on that side of the road is a fire hydrant.

In very snowy areas, the blue reflector may be supplemented by a 3 to 4 foot tall stake adjacent to the hydrant, topped with a circular red reflector. The stake identifies the location of the hydrant for fire departments (who shovel our hydrants after every storm), and for snow plows, to warn them not to plow through the hydrant.