The conical flask was kept in a sink for about 3 or 4 week, was waterfilled, and I have no idea if they grown after the flask was waterfilled or before the flask was waterfilled. We do not work with animals so these arenot any experimental material, but maybe they are soil borne if the conical flask contained soil sample (I do not have any idea what was kept in that flask before it was left in that sink) They were not moving and they were sticked firmly on the glass wall. They had some constriction marks. Length apporox 0.2 to 0.5 cm, Width approx 0.1 to 0.3 cm. colour pale white to brown.
I think this will be a larva. Check this video. If it was in a sink, is very probably than will be a fly. But the specie only will be identified with a genome assay, or taxonomically once they out the pupa.