When I was examining some marine water under a stereo microscope I suddenly saw something I had always been intrigued by. It was a larvacean called Oikopleura .
Larvaceans are primitive chordates related to tunicates .
They look like tunicate larvae but retain this larval shape when they become adult. In fact I did not see what I wanted to see. The most intriguing bit about this larvacean is its housing. And this housing isn't visible since it is completely transparent. But I detected the housing since I saw the small larvacean wiggling its tail to create a water current within this housing.