Charles Ellicott Commentary Numbers 11:7

"And the manna was like coriander seed, and the appearance thereof as the appearance of bdellium." — Numbers 11:7 (ASV)

And the manna was ... — The design of the description of the manna in this place (compare Exodus 16:14 and Exodus 16:31, and Notes in that place; also Article Manna, in “Smith’s Dictionary of the Bible”) was probably to reveal in its true light the sinfulness of the Israelites in complaining about the merciful provision which God had made for the supply of their needs. The dissatisfaction of the Israelites with the sweet bread of heaven, and their craving for the more savory and more stimulating food of Egypt, may be regarded as typical of man’s natural repugnance to the spiritual food which is provided in the Gospel, and his restless cravings for the pleasures of the world.