Yes, there is a moronic acid:
“Moronic acid, a simple triterpenoid keto acid with antimicrobial activity isolated from Ozoroa mucronata,” M. Hostettmann-Kaldas and K. Nakanishi, Planta medica 37.12 (1979): 358-60.
Unwhimsically, it is not unstructured. The structure looks more or less like this:
(Thanks to investigator Deborah Blum for bringing this substance to our attention.)
BOMUS: Traumatic acid