This is a weird and arresting photograph. It makes you look twice. To me it is a rapidly growing species of fungus (mold) which has taken hold on the cat food because the can has been open for a while perhaps in warm weather (3/4 of the cat food is still in the can). It is growing at an inch a day! Definitely a fancy beast! At the tips of the strands are the black spores.
It could be Mucor mucedo which is a fungal plant pathogen.