Cerianthus tube anemones are distinctive, non-photosynthetic marine invertebrates (class Anthozoa) that construct and live within deep, fibrous, parchment-like tubes buried in soft, sandy, or muddy substrates. Popular in marine aquariums for their vibrant, long, flowing tentacles (ranging from white to purple, orange, and green), they require intermediate care, moderate flow, and regular feeding of small meaty foods. 

Key Care Requirements & Behavior

Diet: Carnivorous; require regular feeding (e.g., mysid shrimp, plankton) as they do not possess symbiotic zooxanthellae.

Lighting: They are non-photosynthetic and prefer lower light conditions.

Habitat: Require a deep (at least 7.5cm/3") sand or mud substrate to bury their tube.

Temperament: Generally peaceful, but they have a potent sting and can harm nearby fish or corals if placed too close.

Behavior: Mostly nocturnal, they retract into their tubes quickly when disturbed. 
Physical Characteristics

Tentacles: Feature two sets: long, outer, stinging tentacles for capturing prey and short, inner, labial tentacles for moving food to the mouth.

Size: Can reach up to 40 cm (16 in) in size.

Lifespan: Can live for 5-10 years with proper care.