Halimeda opuntia — Blanketing Prickly Pear Halimeda
Blanketing the reef and building the sand beneath it.
What You Get
Halimeda opuntia, known here as Blanketing Prickly Pear Halimeda, is a calcareous macroalga that forms tight, paddle-like segments which spread outward to create natural mounds and patches. On land, the word “opuntia” refers to prickly pear cactus. Underwater, Halimeda opuntia becomes the reef’s own prickly pear, and as its calcified segments break down, they help form the very white sand that surrounds many Caribbean and Gulf reefs.
Why It Is Algaesome
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Natural reef blanket: Creates low-growing mounds and patches that soften transitions between rock and sand, giving your aquascape a more mature, “grown in” look.
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Sand builder: If its calcified plates break down over time, they can contribute to your reef sand, just as Halimeda does in the wild across the Caribbean and Gulf.
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Herbivore friendly (for you, not them): Most tangs and other grazers find it tough and unappealing, so it often persists where softer macros are quickly eaten.
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Reef system ready: Thrives in tanks with strong calcium and alkalinity, making it a natural fit for mixed reef and macro-focused displays.
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Flexible placement: Anchors to rock, rubble, or sand, and works well in both display tanks and macro-heavy refugiums.
Sizing & Availability
Each order contains two individual clusters of Halimeda opuntia, usually 2 to 3 inches in diameter. Pad size, thickness, color, and overall shape vary naturally from piece to piece. Given good conditions, colonies can slowly expand and may reach up to around 10 inches across over time.
This species is collected from roughly 4 to 70 feet in the Atlantic, Caribbean, and Gulf. It is generally available, though weather and seasonal conditions may affect how often it appears on our list.
Traits
Color Bright to olive green
Ease Easy
Classification Calcareous green macroalgae
Nutrient Uptake Fair
Availability Common, with seasonal swings
Use Groundcover and display macro
Lighting Moderate to high
Flow Moderate
A Note from the Collectors:
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; color returns within a few days under good aquarium lighting and flow.
We ship via 2 Day service on Mondays and Tuesdays only to ensure specimens arrive healthy. You will receive a notification with tracking information as soon as your order ships.
