Cryptic Test No. 1

First to solve the complete cryptic puzzle

5000 GPs

First to solve each line

100 GPs

Cryptic Test No. 1

Elements of iron, sand and bakelite share the mix
When Romans speak, dark chambers spell the word
With collected memories twice reversed and once removed
Forever entombed and never to be heard

Calculated distances based on the speed of light
Motionless yet filled with curdled cries
One ensures the second complements the final third
Thrice exposed: absence confirms all lies


Incorrect responses so far:
Hourglass
TV and Video
Stone Henge

Boom wins 5000 GPs with the correct answer:- Camera and Photograph
A correct explanation of any line still wins 100 GPs.