Meaning of prochloron

pro•chlo•ron

Pronunciation: (prō-klôr'on, -klōr'-), [key]
— n. Biol.
  1. any spherical, photosynthetic, prokaryotic microorganism of the genus Prochloron, occurring in subtropical and tropical habitats in symbiosis with various invertebrates, esp. marine chordates, proposed as ancestral to the chloroplast of green algae and plants.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.