The Ibaloi people, an ancient race from the Philippines, smoked their dead dry for months to mummify them - giving them their firey nickname.
The preserved remains lie in dark caverns 4,000ft up the side of Mount Timbac, near Kabayan in the province of Benguet, 200 miles north of capital Manila.
'It was a spooky and enlightening experience crouched inside a small and damp rock shelter to admire and photograph the mummies really up close.'Mr Zeta-Yep, who has been a travel photographer for seven years, told Mercury Press: 'I have always been fascinated by them.
Mr Zeta-Yep used a DSLR camera on a portable tripod to take the shots with a long exposure, to capture the detail inside the dark caves.
He said: 'After murmuring prayers, our Ibaloi guide lifted the covers. They were lying inside wooden coffins in a fetal position, some with hands over their faces as if to shield the light from our torches.
'The mummies were so well-preserved, we could even see the linear tattoos preserved on their arms and legs.'