Niamh said it was “quite obvious stood out in the grass” with its bright colours.
After finding the mushroom, Niamh took photos and recorded it on a species identification app, where others verified her sighting.
She said she was encouraging others to record their sightings too to feed back into records for the island.
She said: “It’s just important to know what’s on the island and you never know what you will find.”
Niamh said she usually monitored seabirds on Alderney, but recently taken an interest in mushrooms and fungi.
“You never know, you could be the first to discover one on an island or elsewhere,” Ms McDevitt said.