The answer is: A stone like a great millstone

Rev 18 vs 21

In Revelation 18:21, a mighty angel discards a great millstone into the sea, symbolizing the dramatic downfall of Babylon. This isn’t just any millstone; it evokes strength, heaviness, and the grinding of wheat—an essential process feeding people. When the angel tosses this stone, it signifies not only Babylon’s collapse but also a shift in spiritual authority.

Interestingly, Babylon's symbolic significance spans beyond Revelation—it represents hubris, decadence, and oppression throughout the scriptures. It harkens back to the Babylon of the Old Testament, the city of rebellion led by Nebuchadnezzar, stressing a long-standing theme of the struggle between good and evil.

Symbolism in millstones is also layered. Jesus used them in his teachings, warning that it would be better for someone to have a millstone tied around their neck than to lead others astray (Matthew 18:6). This ties the millstone's imagery even closer to the spiritual responsibility we all hold.

Fun fact: centuries before Revelation, Babylon was a real place, once a pinnacle of culture and civilization. Ultimately, its rich history vacillates between wonder and ruin, much like the contrasts woven throughout the scriptures. The downfall of such a mighty entity reveals hope—that over time, deceit and destructiveness faced divine judgment no matter how grand they appeared. The layered narratives push us to reflect on what it means to build or destroy the fragile ties of our own 'Babylons' in life.