الكمأة
A desert fungus described as a form of manna, with its liquid recommended as an eye treatment.
الْكَمْأَةُ مِنَ الْمَنِّ، وَمَاؤُهَا شِفَاءٌ لِلْعَيْنِ
“Truffles are of the manna [given to the Israelites], and their water is a healing for the eye.” (meaning, not a literal translation)
Ibn al-Qayyim discusses truffle liquid mixed with kohl as an eye treatment, while noting scholars differ on whether the benefit applies broadly or was specific to the truffle varieties known in Hijaz.