The choreotrichs are a group of small, marine ciliates. Their name reflects the impression that they appear to dance ('choreo' as in choreography). The group includes the tintinnids, which produce species-specific loricae (shells), and are important because these may be preserved as microfossils. They became common during the Jurassic period, but are first known from as early as the Ordovician, and are important as the only notable record of early ciliates. Often they've been included among the… (More on Choreotrich)