Peter Lindsay Posted almost 2 years ago Are the western vegetarian and vegan movements food fetishes for the rich? Please classify these as plant or animal. Euglena, Trachelomonus, Diatoms. What about a sponge that derives 80% of its oxygen and nutrition from algal cells within its body. The one thing that most identifies plants is the presence of chloroplasts, but these probably started as cyano-bacteria that were engulfed by early single celled organisms. Essentially plants are animals that took cyano-bacteria hostage much as sponges, corals and giant clams now take algae hostage. If you look at the development of life on earth the seperation into plants animals and fungi is very recent, thats why we still share the majority of basic cell structure. Male plants make sperm and females make ova just like people.