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. The cyst forms have been suggested to be affiliated to
Chitinozoans, although other studies suggest Chitinozoans to have affinities to larger marine animals, and not tintinnids. Often they have been included among the
oligotrichs. Tintinnids seem to be an excessively specious group as over 400 living species have been described, based on characteristics of the lorica or shell.