False Irish moss is a red seaweed, resembling a stiff, thinner version of Irish moss. The fronds have thick rims and seem to have a channel flowing through them. This seaweed is found in the lower to mid tidal zone which is not exposed for too long, often attached to rocks. Sometimes, you find this seaweed higher up on the dike or on rocks, but then growing under knotted wrack plants. Like some other red seaweeds, false Irish moss is used in the food industry as a thickening agent and stabilizer. If the E-number 407 is among the ingredients, that could mean you're eating this seaweed. In Ireland and Scotland, they use it together with Irish moss to make a drink which is reputed to ward off colds and flus.