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n.1.(Biol.) A cyst in which some unicellular organisms temporarily inclose themselves, from which they emerge unchanged, after a period of drought or deficiency of food. In some instances, a process of spore formation seems to occur within such cysts.
References in periodicals archive ?
Marine sediments off Cata-lonia contain coccoliths (more than 80% Emiliana huxleyi), but hardly any diatom valves, and the few that do persist are hypnocysts, resistant cells with thickened walls, or equally robust coastal diatoms.