Depiction:
The fountain depicts a vulture's nest in which a vulture with outstretched wings brings food to its young.
History:
In the 16th century, the pelican was considered a symbol of care, so this is presumably a symbolic representation of the nourishing pelican.
For the fountain, the pelican was replaced by a vulture, as the location chosen was "Geiersberg" (Vulture Mountain).
Reference:
https://nuernberginfos.de/brunnen-nuernberg/geiersbrunnen.php