...wrong.
Algae is NOT a plant. It is called a 'plant-like protist'. A common misconception is that algae is a plant. Even my school science book (outdated) has algae listed under plants. Diatoms(a brown algae) are small animals that have a cell wall covered in shiny material, and under a microscope they look like jewels. Another Plant-like protist is the Euglena, which composes part of algae's makeup. The reason they are not plants nor animals is because animals do not use photosynthesis, while plants do. Plants do not reproduce via rapid cell division, animals do.