Unknown food spoilage mold. The photographer notes that "it has found a home on some forgotten leftover elderberry syrup of mine." We (PT, that is) managed on short notice to find an expert, who writes, "Molds are notoriously difficult genus to identify on natural substrates" and adds that it is "possibly Aspergillus or Penicillium sp.," but there is no way to be sure without microscopy or DNA.
