In the first scene of Indiana Jones and the Raiders of the Lost Ark, we see a booby trap where a series of spikes are thrusted out of a wall, and are triggered by "walking into the light". I think in the story of the film, this was meant to be something related to superstition (or the beliefs of the tribe) that triggered it. The Indiana Jones Wikipedia page says that this was a temple built by a Chachapoya tribe(s).
With ancient technology of any civilisation, would it be possile to develop a light trigger mechanism, where the sudden absence of light could cause something to happen? I guess it is possible over a long period of time with photosynthesis, but I'm looking for something near instant.
- The system must not contain any living animals to function. Any types of plants/fungi, if can work, are alright
- I think for the moment, it may be best to not worry about day/night cycles (just assume that when the sun goes down, depending on how the system works, it will be triggered)