At first glance, you would think that there is a strange Pyramid out in the distance, but in reality, it is the shadow of the awkward looking volcano in the bottom center of the image. So why then does the shadow appear to be in the shape of a pyramid with a perfect triangular tip? Well, the answer is very simple, it has to do 100% with Perspective.
The Photo was taken by Juan Carlos Casado from the top of the Teide, he said:
A key reason for the strange dark shape is that the observer is looking down the long corridor of a sunset (or sunrise) shadow that extends to the horizon. Even if the huge volcano was a perfect cube and the resulting shadow was a long rectangular box, that box would appear to taper off at its top as its shadow extended far into the distance, just as parallel train tracks do.