It is NOT a good idea, and normally fails, not always right away, but evenetually
sometimes they do fine for months, or even a year or so, until they get bigger, but disaster is often waiting.
Large tanks, sometimes do help to prevent this.
there is even a member who had posted photos of his sharing an anemone, but That is NOT the norm. And in no way should be counted on. It is only a probable disaster waiting to happen, but is sometimes(rarely) avoided.