This fine piece about invasive sea squirts states that the critters maintain an unappetizing surface pH of 2. Does this make these mats harmful to touch?

Andrew J. Dolson
Richmond, Va.

Robert Whitlatch of the University of Connecticut, who grows Didemnum in the lab, says it’s fine to handle for short periods of time, “though I wouldn’t attempt to taste/eat them, lick your fingers, or rub your eyes after you’ve been handling them.” —J. Raloff