Watsoniomyces obsoletus 8

Watsoniomyces obsoletus, growing on a chalk fragment, Cliveden, Buckinghamshire, showing the endolithic thallus and minute, immersed apothecia. The surface of the chalk is often slightly gelatinous and with an orange hue which may be due in part to the decaying sheaths of the Scytonema photobiont. The apothecia are a dark reddish-brown colour, becoming more obviously red, and more conspicuous, when wet.