Perithecia

Pear shaped ascomata present in a small number of lichens. Most likely encountered in Colorado in Dermatocarpon, but also present in various crustose lichens. Often they are immersed in the thallus. The presence of perithecia is important for differentiating dermatocarpon from umbilicaria.

Without a microscope they look virtually identical to pycindia.

The small black dots here are perithecia. Dermatocarpon moulinsii – Wray, CO