There are six major 'divisions' of fungi and those which produce sac-like structures are the division called Ascomycota. It is therefore most likely that the new fungus can be classified within this division. This group produces spores in distinctive sac-like structures. Members of the division include yeasts and penicillin.
I believe it is the ascending loop of henle. In the ascending portion, the loop becomes impermeable to water and instead the cells of the loop, actively reabsorb the solute; thus water is not reabsorbed but ions are readily reabsorbed. As the ions are reabsorbed the concentration becomes more and more hypotonic until it reaches 100-150 mOsm/L. Therefore, the ascending loop is called the diluting segment of the nephron due to its ability to dilute the fluid in the loop from 1200 to 100 mOsm/L.
Humans and animals need oxygen to survive so oxygen in the atmosphere maintains life on earth for humans and animals to breathe to survive