An example of metaphor in public science discourse:
GV: "What sort of part of the jigsaw puzzle does it complete to bring this species [water voles] back in particular?"
AL: "They are a missing part of the food chain. So, through their burrows they will dig up through the soil, they will bring soil nutrients to the surface, which helps with vegetation. They themselves are consumers of vegetation, so they'll nibble bits of plants, leaving room for other plants to come through so changing the plant composition of the banks. And Then, of course, they are a food source for predators, so foxes, herons, otters, hopefully not mink, we hope that we've not got mink here anymore, but also birds of prey so you know, really vital part of, the missing Mars bar, essentially, of the food chain."
Inside Science
Dr Ashley Lyons, Conservation Scientist, RSPB, was being interviewed by Gaia Vince on an episode of BBC Inside Science
I am considering the 'missing Mars bar' reference as a metaphor, but the qualification 'essentially' could be seen as intended to be marking the reference as figurative, as in a simile (like the missing Mars bar)
Read about examples of science similes
