The blaze last Tuesday destroyed gorse, heather and bilberry over 70,000 sq m (753,470 sq ft) - about the size of 10 football pitches.
The fire prompted more than 200 calls to Cornwall Fire and Rescue Service and was dealt with by five fire crews.
A disposable barbecue caused the blaze, the fire service said.
Jon James, environment manager at Cornwall Council, said it was the "worst time of year" for the fire to happen with nesting birds, small mammals and reptiles among the casualties.
"With the ground being relatively dry at this time of year the fire has burned quite deeply in places and the ground will take many years to recover," he said.
Nathaniel Hooton, from the fire service, said the blaze highlighted the dangers of disposable barbecues.
A 90 ft (27m) granite cross built in 1826 stands at the peak of Carn Brea and a chapel built in 1379 has been converted into a restaurant further down the hill.
Land damaged by a massive gorse fire at Carn Brea in Cornwall will take "many years to recover", according to local council environment bosses.