Michael Marshall in New Scientist:
Species: Mesodinium chamaeleon
Habitat: seawater around Scandinavia and North America, chowing down on a new generation of slaves
Many animals transform themselves almost beyond recognition in the course of their lives. Caterpillars become butterflies and tadpoles become frogs, and if we couldn't watch them do so we might not even suspect that the two stages were the same creature.
Spectacular as these shifts are, they are only shape-shifting. A tadpole and a frog are both animals, so both must take in food from their surroundings.
Not so Mesodinium chamaeleon. This newly discovered single-celled organism is a unique mixture of animal and plant.
Plant pals M. chamaeleon is a ciliate – a kind of single-celled animal covered in hundreds of tiny “hairs” called cilia. It was discovered in Nivå bay in Denmark by Øjvind Moestrup of the University of Copenhagen, also in Denmark, and his team. Other specimens have since been found off the coasts of Finland and Rhode Island.
Ciliates using their hair-like cilia to motor around rapidly in water. Most get their food by eating other organisms, rather than by synthesising the nutrients themselves. This marks them as quite animal-like.