Blue-green algae get a bad press – but we owe a debt of gratitude

While some cyanobacteria are among the deadliest organisms in the world, others help us flourish

Blue-green algae, or cyanobacteria, come in many forms and have generally got a bad press, mainly because five of the 2,000 identified species can produce some of the deadliest toxins known to science.

At the same time, they are among the oldest organisms in the world, dating back 2.1bn years, and we owe them a debt of gratitude.