The seaweed growing along India’s coast may be closer to you than you think.

It could be helping your ice cream stay creamy, keeping the ingredients in your toothpaste from separating, or even forming part of a medicine in your cabinet.

You may never taste it, see it or know its name.

Along India’s 7,500-km coastline grow more than 800 species of marine algae, from red seaweeds clinging to rocks off Tamil Nadu to bright green varieties found in shallow coastal waters. Around 60 of these species have commercial value, and some already make their way into foods, cosmetics, pharmaceuticals and laboratories.

Take a tub of ice cream. Its smooth texture and lack of icy crystals can come partly from carrageenan, a natural thickening and stabilising agent extracted from red seaweed. The same ingredient can help keep cocoa evenly suspended in chocolate milk.

And that is only one example.

Three major seaweed extracts, carrageenan, agar and alginate, already form a global industry worth more than half a billion dollars. A 2023 World Bank report estimated that 10 emerging seaweed markets could grow to $11.8 billion by 2030.

Their appeal also lies in how they are grown. Seaweed needs no agricultural land, freshwater, fertiliser or pesticides, making it especially relevant as pressure on land and water continues to rise.

From “green caviar” and laboratory agar to toothpaste, snacks and medicines, here are eight seaweeds found along India’s coastline and the surprising places they show up in everyday life.

1. Kappaphycus alvarezii: In chocolate milk and ice cream 

Found along: Tamil Nadu coast, especially Rameswaram and Pamban Island

Walk through the shallow waters near Rameswaram at low tide, and you'll likely see rope lines strung between wooden poles, with thick, rubbery reddish-purple fronds tied along them. This is Kappaphycus alvarezii, a seaweed that........

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