A common housefly has a 4 stage cycle (egg to adult). But I hit one with maggots crawling out its belly. Why?

Question

I know the complete metamorphosis of a common housefly starts from egg, larvae, pupa and finally adult fly. The one I hit had a shinny body (dark purplish one) was slight rounder and larger one. Also, it made louder buzzing nose and normally flies a little slower that the dull brownish ones. When I hit it, instead of seeing smashed eggs, among other things, I saw maggots crawling out.

Answer 1

cause that's gross, not sure, maybe it was a different kind of fly, like a morphing one