Planula larvae exhibit positive phototaxis , swimming towards light to reach surface waters, where they drift and grow before descending to seek a hard surface to which they can attach and begin a new colony. They also exhibit positive sonotaxis , moving towards sounds that emanate from the reef and away from open water.  High failure rates afflict many stages of this process, and even though millions of gametes are released by each colony, few new colonies form. The time from spawning to settling is usually two to three days, but can be up to two months.  The larva grows into a polyp and eventually becomes a coral head by asexual budding and growth.