Vivarium is a 2019 science fiction psychological horror film directed by Lorcan Finnegan.
The film opens with a short clip showing the parasitic lifecycle of cuckoos, who lay their eggs in the nests of other birds. Once hatched, the cuckoo pushes the mother bird’s young out of the nest and is then tended to by the surrogate mother. By the end of the clip the cuckoo is disturbingly larger than the mother bird, greedily eating all she has to offer.
The movie vivarium looks like a large social experiment in which the young couple are put in a lab box like mice to observe their behaviour in a closed environment for long periods of time.