What they've done before the commercial versions is using, like, five-gallon buckets of this drill hole in the bottom, so they can plant through, put some dirt in and hang it up.

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The physical anthropologist who carried out the examinations, Professor Andrea Cucina said the work could have been done to treat tooth decay, and suggested some plant or other material, which would have since decayed, could have been inserted into the hole.

BBC: Prehistoric dentistry evidence found