Bonjour,
On a trouvé ce petit asco orange avec Grimmia pulvinata sur un mur calcaire dans le nord de l'Angleterre. C'est Octospora musci-muralis?

On Grimmia pulvinata, limestone wall, Peak District, N. England, 31/12/2016.
Ascocarp 3 mm diameter. Rather tough, with paler scurfy margin to bright orange disc. Firmly attached to the moss.
Underside sessile, whitish, roughened but without "rhizoids".
Spores: 25-30 x 9-10 (9 spores) expelled on squashing asci. Two oil droplets.
Asci: 150-170 x 18-20. Easily broken on squash preparation. No blueing with Lugol, but dextrinoid reaction in developing asci.
Paraphyses: approx 150-170 x 3. Swelling to 7 at tips, which are bent.
Using the reference below (Trans. Br. mycol. Soc. 58(1): 147 (1972) I suspect this is Octospora musci-muralis, but in my specimen all spores had 2 oil drops, whereas they are described on the website as having 1 or 2 oil drops.
http://www.octospora.de/Omuscimuralis.htm