pyramidical

adjective [原级]角锥状的；金字塔形的

Perhaps the positions of the three pyramidical images in the crystal sphere hold the long-sought key to finding a fourth, as yet unfound.
也许在水晶球体三个金字塔形图像的位置持有苦苦寻找发现第四个金字塔的钥匙，目前为止还没有发现。