Is coral an animal, plant, or rock?

Corals are animals because they do not make their own food, as plants do. Corals have tiny, tentacle-like arms that they use to capture their food from the water and sweep into their inscrutable mouths.

I thought this is a plant? They have a mouth? Which made them an animal?

That is according to experts that made them animals. Coral polyps come out of their skeletons at night to feed, stretching their long, stinging tentacles to capture critters that are floating by. Prey are pulled into the polyps’ mouths and digested in their stomachs.