White crustose lichen with quite large black pimples.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
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The black discs here seem to have a proper margin, making them apothecia. Thelidium papulare (note the correct spelling) has dome-like perithecia with an opening (ostiole) at the top, visible here:
This might be a Porpidia sp., but a look at the spores under a microscope is probably necessary.
Thanks, Nigel - correct spelling noted!
The perithecia was certainly very dome-like. I wasn't aware of an ostiole on the top but will have another look.
I don't own a microscope more's the pity, the best I can do is a magnifying glass, but that's probably not enough.
I agree with Nigel that this is most likely a Porpidia species, but most need microscopic examination and chemical testing.
Pretty good lichenologists confidently name many of them in the field. Very good lichenologists don't!
Since I am not a very good lichenologist yet (and a long way to go), I'll suggest this is Porpidia macrocarpa, but this is merely a suggestion.
Lat/Lng: 57.6959, -2.8091
OS grid ref: NJ518676
Between the path and high water mark.