It's actually all cubes. To get the look of pyramids you just move veticies to overlap and to get the extruded look you put two cubes back to back. I can add the 3d model file as well.
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Moving vertices to overlap to do things like make a cube look like a pyramid is unfortunately also against the theme: "You may move vertices, but do not make vertices of the same mesh overlap positions."
I don't know if it will actually let you add a new file or not during the voting period but technically you should have the model available anyways as per the jam rules: "Please submit an animated Gif spin of your model, the model txt, and if you have it, the texture png."
At any rate your model is very cute it just goes a bit against the spirit of the limitation.