Question

then if you keep a piece of moist bread in a corner of a room for a long time

Answer 1

if we keep a piece of moist bread in the corner of room for a long time it would have fungus grown on and we would see some tiny pores on the Bread and after a long time the fungus would have eaten the bread by changing it into soluble form

Answer 2

if you do so then the bread will develop mould or bread mould or fungus which has some kind of greenish color or yellow one
hope it helps