Time for eyespots, not just because of the irreducible complexity silliness, but because I actually think these are awesome. The first time I saw one under a microscope, I got even more excitable than usual (Trust me, when it comes to nature, my standard state is very excitable!) This is a euglenoid (picture from http://www.okc.cc.ok.us/biologylabs/documents/Zoo/Euglenozoa.htm) The arrow points to a photosensitive spot, also known as a stigma. This is FAR from being what we would consider an eye, but, it gives the organism an ability to sense light, and therefore sense when something (a predator for example) is in the way of the light. The ones I have seen are not as clear as this, and can be at either end of the organism, but is always present in euglenoids. I have used Euglenoid rather than the phyla name, to avoid the “euglenoza/euglenophyta” discussion. I usually use Euglenophyta, but that is purely because that is the term I heard for them, and it kind of stuck. If you want to look up more about the phyla in general, either term works. Euglena is the term for the genus. I try to avoid getting caught up in the ever changing taxonomy of organisms in general though, so will mostly use generic terms.