Avrainvillea rawsonii - Poseidon’s Loofah
This spongey algae reigns the sea floor.
What You Get
Poseidon’s Loofah is a thick, sponge-like green macroalga that grows from a single holdfast into a rounded upright pad. The surface feels velvety and solid, more like a reef sponge than a leafy or feathery macro, which gives it a very different look from most greens.
In the wild it dots sandy bottoms and low rock ledges in shallow tropical water, where each “loofah” rises just above the seafloor. In the aquarium it plays the same role, breaking up flat sand areas and adding a bold, sculptural accent among finer grasses, reds, and gorgonians.
Why It Is Algaesome
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Sponge-like structure: Thick, cushiony fronds add real three-dimensional texture to the aquascape.
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Visual anchor: Works beautifully as a sand bed focal point or a soft edge between rockwork and open substrate.
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Great contrast: Pairs well with finer or branching macros to create a layered “macro garden” look.
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Hard to resist, yet rarely eaten: Many herbivores tend to ignore the dense, spongey tissue once it is established.
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Steady and reliable: Does well in stable systems with moderate light and gentle to moderate flow.
Sizing and Availability
Each portion is roughly 2 to 3 inches tall and about 2-3 inches across, with natural variation in fullness, contour, and shade of green. When possible, specimens are collected attached to a small piece of shell or rubble for easy placement. Availability is selective and can be seasonal, depending on conditions at the collection sites.
Traits
Color Deep Brownish-Green
Ease Easy
Classification Green macroalgae
Nutrient Uptake Low to Moderate
Availability Seasonal and limited
Use Display
Lighting Moderate to bright
Flow Low to moderate
A Note From the Collectors
Poseidon’s Loofah does best in stable systems with consistent salinity, alkalinity, and detectable nutrients. Avoid frequent relocation once it is placed, and aim for gentle to moderate flow that keeps the surface clean without blasting it directly.
Every macroalga we offer is hand-collected, acclimated, and observed by our team before shipping. While we carefully try to remove other algae, sponges, and tiny hitchhikers, it is possible that a few “goodies” from the reef may tag along. It is a natural part of receiving genuine wild-collected specimens.
Many species may arrive paler or whitish in color. This is completely normal. Macroalgae shift their pigments inward during transport to protect from light and stress, and color usually returns within a few days under good aquarium lighting and flow.
We ship via 2-day service on Mondays and Tuesdays only to help ensure specimens arrive healthy. You will receive a notification with tracking information as soon as your order ships.
