It would help all of us greatly if you could provide the magnification for the image, the location in which you found the structure (in culture, on a plant or other substrate, on the body of the larger fungus?), and what class, genus, or even species of fungus you believe to have produced it. Were the other parts of the fungus hyaline or dematiaceous?

Thanks a lot for your kind help. The size of the small one is over 20 um, and the large on is over 30 um. They are collected from the South China Sea, most likely Pleistocene or Pliocene. They are the fossiled single spores, no mycelium or other organism connecting with them.

Dear Yunfa,

It is difficult to make conclusions from such a small photo. May be a book provided with plenty of fungi fossils` photos will be helpful:

Taylor TN, Krings M, Taylor EL. 2015. Fossil fungi. Elsevier. ISBN 978-0-12-387731-4.

http://store.elsevier.com/Fossil-Fungi/Thomas-N-Taylor/isbn-9780123877543/

Best regards,

Elena

Thanks a lot, I got this book.

This database may be useful to you:

http://advance.science.sfu.ca/Kalgutkar_and_Jansonius/