What is a genus of tough, leathery seaweeds, usually of a dull brownish green color; rockweed. Note: Formerly most marine alg were called fuci called?

fucus — (Bot.) A genus of tough, leathery seaweeds, usually of a dull brownish green color; rockweed. Note: Formerly most marine alg were called fuci. (Webster's 1913.)

Sources