ABOVE: The ciliate Pseudoblepharisma tenue harbors both green algae and purple bacteria as symbionts. SEBASTIAN HESS M ore than a century ago, a German schoolteacher named Alfred Kahl made a career ...

Under a strange pink-purple glow, illuminated panels buzz and ... It also grows a type of bacteria called Arthospira, also known as blue-green algae, as it shares similar properties with microalgae.