White Bubble Coral (Plerogyra sp.)

Plerogyra's bubbles aren't decorative — they're hydrostatic sacs the coral inflates during the day to maximize surface area for its zooxanthellae, then deflates at night to expose the feeding tentacles underneath and go hunting. Watching that transition happen in real time is one of the more oddly mesmerizing things you'll see in a reef tank. It carries a real sting despite the pillowy look, with sweeper tentacles that reach further than the bubbles suggest, so it needs breathing room from anything it can reach.

Care level: Easy · Light/Flow/Placement: Low-moderate light, low flow, bottom-to-mid tank with space from neighbors · Max size: 6"+ colony · Diet: Photosynthetic, occasional meaty feeding at night