This video shows an antheridium (i.e., male sex organ) of Elaphoglossum glaziovii (Fée) Brade releasing its antherozoids (i.e., motile male gametes; sperm cells). As the ring cell of the antheridium slowly absorbs water from the environment, it expands into the antheridial cavity pushing the antherozoids against the cap cell. Eventually, the antherozoids are released and swim away.