C. elegans, a tiny free-living worm, was the very first animal species to be completely genetically sequenced and operates with many of the same genes that are found in human beings.
It is used by scientists as a model system to gain a fundamental understanding of the basic principles of life.
C. elegans is so simple it doesn't have a brain, only a minimal nervous system of 302 nerve cells (as opposed to the 100 billion or so in the human brain).
This 1mm long worm exhibits a wide range of behaviour, including foraging, learning, memory and even social behaviour.
Scientists are fascinated with this tiny worm, anticipating that this will be the first animal species to be completely understood.