Carchesium is a genus of usually colonial peritrich ciliates in the Vorticellidae with a spirally contractile stalk.

[1][2] The inverted bell-shaped cells have an oral lip as in Epistylis.

The genus has a cosmopolitan distribution in freshwater and is a common part of the fauna of the aerobic stages of waste water treatment plants, such as activated sludge and trickling filters.

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