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
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Parasitic fun fact; did you know it’s estimated almost 50% of all life on earth is parasitic? [spoiler]At least, I think it was 50%. I’m going off memory here, so take that with a grain of salt; I just know it was areally high number![/spoiler]