I like this logo because it is instantly recognizable. It is also clearly portrays what type of organization it is (animals, endangered species). I also tend to like images that use negative space to 'trick' the eye into seeing a continuation of a line where there isn't one.
And since I clearly misunderstood the assignment the first time, let's try this again. Here is something I like the design of: an hourglass. They are easy to make, have numerous uses, the design is minimal, aesthetically pleasing, and efficient. They can also be iconic, as in the hourglass from Wizard of Oz. They are also often used symbolically.
