Irish moss may refer to: Chondrus crispus, a commonly gathered seaweed; a clarifying agent in beer brewing Mastocarpus stellatus, a less commonly gathered seaweed Sagina subulata, a terrestrial plant with needle-like leaves Soleirolia soleirolii, a terrestrial plant with round leaves Arenaria verna, a terrestrial plant in the genus Arenaria Gracilaria, a genus of seaweed Irish moss (drink), a beverage in Jamaican cuisine made from Gracilaria Gelidium amansii, a genus of seaweed which yields agar agar