This is a product of activity prehistorical glacier. In my youth I have been an alpinist and wandering on numerous mounting systems of the wast USSR. I have seen such phenomenons frequently on the mount glaciers. It has been made up of ice and consisted a purl and babble water within it and named "lavatory pan" or "toilet bowl". It is known also as the "devil's mortar" among Finns (in sense - pestle).
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