This is Orange Pore fungus, commonly called "Ping-pong bat" fungus due to its distinctive shape.
The scientific name was Favolaschia calocera but it's now been deemed to be Favolaschia claudopus.
Only known in Britain since 2012 ut was thought to have originated in Madagascar but it now seems that may have just been a "stopping off" place as it was known in New Zealand before that.
It has now colonised many woods in the South of Cornwall with these being found at Tregrehan near St.Austell. Special thanks to Iain Stewart for finding them and letting me photograph them.