Fu·coid'al adjective 1. (Botany) Fucoid. 2. (Geol.) Containing impressions of fossil fucoids or seaweeds; as, fucoidal sandstone. Found on http://www.encyclo.co.uk/webster/F/83
In geology, the term fucoidal refers to rocks containing impressions of fossil fucoids or seaweeds such as fucoidal sandstone for example. Found on http://www.probertencyclopaedia.com/browse/HF.HTM