So, another quirk in Revelation occurs in 16:7, when the seven angels are pouring out bowls of divine wrath upon the earth and sea. In the middle of it, the "angel of the waters" speaks of the Holy One as judge, who is righteous and offers proportional punishments: those who shed the blood of the saints get blood to drink (the waters turn to blood as in the Egyptian plague).
In response, the heavenly altar itself speaks (NRSV): "yes, O Lord God, the Almighty, your judgments are true and just."
Interestingly, it seems the throne also speaks: "And from the throne came a voice saying, 'Praise our God, all you his servants, and all who fear him, small and great'" (Rev 19:5).
This could just be a disembodied divine voice coming from the throne - or the throne is alive, animate. It is something that occurs intermittently throughout Revelation, too, usually before breaking out in a hymn.
I know that in the Songs of the Sabbath Sacrifice the heavenly sanctuary and its various elements are animate and the divine throne in the much later Hekhalot Rabbati also gets up and bows before God. But has anyone heard of the speaking altar before?