Agardhiella subulata (C. Agardh) Kraft & M.J.Wynne is a bushy, red seaweed native to the East Coast, from Nova Scotia to the Caribbean. It has numerous fine thin, fuzzy branches, is rosy to maroon, and grows to about 100 mm tall. It usually grows on rocky substrates, and sometimes epiphytically on other algae in shallow water, down to about 10 meters. In 2010–2012 it was collected and genetically identified, in Lake Merritt, Oakland, and Alameda, both in San Francisco Bay. This alga has probably been overlooked due to its similarity to the native alga Sarcodiotheca gaudichaudii (Hughey and Miller 2018). Agardhiella subulata has also been introduced to the Netherlands and several sites in the Mediterranean. Likely vectors include plantings of Eastern Oysters, ballast water, and hull fouling.