I spotted this as yet unidentified moss growing inside the umbilicus of a live Strawberry Snail Trichia striolata at NBGW yesterday. Probably not that unusual, but thought it a bit quirky all the same! I still have the snail but have not yet sampled the moss within so any suggestions welcome (I guess it's going to be a calcicole). Also I would be interested to hear if anyone else has encountered anything similar.
... finally got round to looking at the snail-moss and it's Rhynchostegiella tenella