Species of gold coral can be parasitic, such as the Hawaiian [i]Kulamanamana haumeaae [/i]. It will attach to its host (such as bamboo coral) and begin growing over top of it and expanding. This rate of expansion has been seen at an estimated rate of 2.2cm/year. Source: https://deepseacoraldata.noaa.gov/library/gold-coral-kulamanamana-haumeaae-in-hawaiian-deep-coral-assemblages