Money Plant

Care at a glance

Overview

Halimeda is grown as a decorative reef macroalga rather than a heavy nutrient exporter, prized for its coin-chain shape and its resistance to being grazed. It does best under moderate to strong light with a stable calcium level of roughly 350 to 450 ppm and good alkalinity, since it must build a calcium carbonate skeleton to grow, which also makes its growth slow. Unlike Caulerpa it is not invasive and will not overrun a tank, but it is less tolerant of high nitrate and phosphate and dislikes heavy pruning, so it suits a well-maintained display more than a nutrient-abused refugium. It roots into sand and adds pod habitat while quietly building substrate.

In the wild

A calcareous green macroalga of tropical reefs worldwide, made of chains of flat, coin-shaped calcified segments joined end to end. It roots into sand and rubble around reef bases and lagoons where stable calcium and alkalinity let it lay down its hard skeleton, contributing significantly to reef and beach sand over time.

Good to know

Halimeda deposits aragonite (calcium carbonate) crystals within its tissues, so it is a major calcifying alga and a globally important producer of carbonate sediment. Each plant is coenocytic, and calcification is tied to photosynthesis: the alga raises local pH as it consumes CO2, which favors carbonate precipitation between its filaments. Because its segments are armored with calcium carbonate and it produces deterrent metabolites, most herbivorous fish leave it alone.

Did you know

Halimeda is nicknamed the money plant because its stacked round segments look like little green coins glued end to end, and when the plant dies its calcified segments break down into the white carbonate sand that builds tropical beaches.

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