All of the elements in the periodic table are monoatomic except the 7 elements that are diatomic atoms. These 7 elements are hydrogen, nitrogen, oxygen, chlorine, bromine, iodine and fluorine. Monoatomic substances are those elements that are stable by themselves.
I believe the answer is gills
Fish's use gills to breathe, so tadpoles should use gills too
hope this helps
(got the info from a documentary i watched a couple years ago)
the plants would grow and reproduce working together forming nutrients from their dropped leaves / branches etc causing insects to come along and do the same along with animals and a keystone species to form a revolving ecosystem continuing an energy moving process
