Theophylact of Ohrid

And the twelve baskets of leftovers remain for the same purpose, so that each of the apostles, having carried a basket on his shoulders, would always keep the miracle in memory. And the fact that He not only fed such a multitude of people but also left over an abundance is a sign of the superabundant power in Christ. Moses, though he gave manna, gave only enough for each one's need, for in what was left over, worms bred. And Elijah, feeding the well-known widow, provided exactly as much as was sufficient for sustenance. …

Commentary on Mark ↗