In science fiction, the diet of extraterrestrials is an interesting mix of energy absorbtion. Usually it is simply just us but there are the proposed symbiotic relationships with bacteria that has radiation as the primary energy source. However from an engineering point of veiw the actual needs and transfer of energy should be'question one' to be answered.
So do they eat and if so what? radiation, Strawberry ice cream, animal mutillations, twinkys, chemical reactions or atomic? I wonder what a real alien schmeer would look like.

Would a shared banquet be unifying or a surprising disgusting event?