important greenhouse gas and part of the carbon cycle coccolithophorid: small, single-celled phytoplankton that have flagellae and calcareous plates in their cell walls.
(small, single-celled phytoplankton; have; flagellae and calcareous plates; L:in their cell walls)
small, single-celled phytoplankton
have
flagellae and calcareous plates L:in their cell walls