diatom

Diatoms are algae with hard parts. They make up a major part of the plankton found in fresh and salt water environments. Usually, diatoms exist as single celled free floating organisms, but they can also be colonies of several single cells. Their tiny little 'shells' are made up of silica (these shells are called "fustules"). The fustules have a characteristic shape that goes with each species, and since these are hard (essentially, made of glass) they are often well preserved in sediments. Thus, diatoms actually provide an excellent, even if very tiny, fossil record. In addition, since…
These were too cool not to share here. We are like the Robin Hood of scientific imagery... sort of Larval crab Copepod Diatoms To make matters worse... we can't find the original article these came from... it's over at National Geographic in some article about plankton or something...