Olivier Dugornay (CC BY 4.0)
Pineapple Sponges
Sycon and Scypha spp. (family Sycettidae)
Small calcareous filter-feeding sponges that pull particles and dissolved waste from the water and never sting, spread over corals, or prey on anything.
Identification
Small white to cream fuzzy tubes, usually well under 2 cm tall in aquariums, shaped like tiny pineapples or cotton-swab tips: a plump barrel body with an open hole (osculum) at the top ringed by a crown of fine spicules giving a hairy fringe. They grow fixed in place on shaded rock, in sumps, overflows, and other low-light, moderate-flow areas, often appearing in clusters in newer or nutrient-rich systems.
Often confused with
Pest sponges and, for beginners, aiptasia. Against aiptasia the tell is structure: a pineapple sponge has no tentacles, no mouth disc, and no ability to retract, sway, or relocate — it is a rigid, fuzzy tube with a single open top. Aiptasia is a translucent brown anemone with a ring of tapering tentacles that pulls into a ball when touched. Against invasive encrusting sponges, pineapple sponges stay as small separate tubes and typically fade on their own as silicates and nutrients drop.
Natural predators
No natural predators are listed.
Field notes
Helpful filter feeders that consume fine particles and bacteria, and a common, short-lived bloom in young tanks. Populations usually shrink away as the system stabilises, so the best response is to enjoy the free filtration.