It is manna
Exodus 16:15
16:15 It is manna. This is the altogether miraculous “bread from heaven” (John 6:31) provided for the millions of Israelites in the wilderness for forty years, always sufficient, never too much, never on the Sabbath. Skeptics have tried to identify it with various naturally occurring substances of the desert, but none can meet the specifications set forth in Scripture. Its supernatural provision was taken by Christ Himself as a type of His own coming down from heaven to give “life unto the world” (John 6:33). The quail (Exodus 16:13) were natural enough, but the timing and quantity of their coming constituted a providential miracle.