Spine Coral

About

Spine coral (Hydnophora pilosa) is a stony coral from the Indo-West Pacific, found across shallow reef zones that are sheltered from heavy surge, typically from the surface down to around 30 meters. Younger colonies tend to grow in encrusting, plating, or low mounding forms, but mature colonies develop into compact hemispherical shapes built from fused, tightly packed branches. Those branches sometimes flatten toward their tips, giving larger colonies a layered, textured look. The most immediately noticeable feature in the aquarium is the polyp behavior. This coral extends its tentacles both day and night, which is less common among stony corals and gives Hydnophora pilosa a consistently fuzzy, almost soft-coral appearance even in full light. The tentacles are long relative to the coral's body, shaggy in texture, and all roughly the same length, tipped in white against polyps that run dark brown to blue-grey. That coloration is understated compared to some reef corals, but the constant polyp extension more than makes up for it visually. Care falls into the intermediate range. This isn't a beginner coral, but it's not especially demanding either. Moderate lighting and flow suit it well, and it should be given some space on the reef, as those extended tentacles can irritate neighboring corals.