Plant
Algae comprise several different groups of organisms which produce food by photosynthesis and thus have traditionally been included in the plant kingdom. The seaweeds range from large multicellular algae to single-celled organisms and are classified into three groups, the brown, red and green algae. There is good evidence that the brown algae evolved independently from the others, from non-photosynthetic ancestors that formed endosymbiotic relationships with red algae rather than from cyanobacteria, and they are no longer classified as plants as defined here.
Caulerpa taxifolia
It is thought that the seaweed was accidentally released into coastal waters of the Mediterranean Sea (just below Jacques Cousteau's) Oceanographic Museum of Monaco in 1984. Ten years later, the claim was made that "Caulerpa" had grown to cover , and was preventing native plants from growing. This concern earned the algae the dubious nickname "Killer Algae" after the title of a book written on the subject. Its author, Marine biologist Alexandre Meinesz first discovered the alga in the 1980s, and requested the help of the Monaco Oceanographic Museum, which sat right next to the first known "C. taxifolia" patch. The director of the museum argued that this invasion probably happened naturally, the result of ocean currents carrying a tropical species into the area. The parties bickered publicly for years over whether the species was natural or invasive, and whether the museum had released it or not, at the expense of sound scientific research on the species and its ecological significance.