Why are still corals an animal?

Coral polyps are animals, not plants. Previously, there was a lot of controversy about the belonging of corals to a particular kingdom. These organisms, although they lead an attached way of life like plants, are not autotrophs. That is, they themselves cannot produce organic matter in the process of photosynthesis. They also have sexual reproduction, which is similar to the reproduction of animal organisms. We can also say that corals do not have those organelles of cells that are characteristic of plants.