This is a Taihu stone, they are awesome
A Taihu Stone is a form of garden art which originated around 700 years ago in Chinese gardens and represent humans influence and collaboration with nature. These rocks are found on the countryside and chosen based on their unique shape. When a rock is selected, the artist carves into it to accentuate its features, then he places it in a river for around 30 years to let the water erase any manmade marks. A generation later, a descendant of the artist retrieves the boulder from the river as a finished piece and the work repeats.
At one point the soil offered a place for flora and fauna to grow referring to the sculpture’s original intent as a garden piece. Its placement near the Japanese teahouse refers its history as these rocks are collected and revered by the Japanese.
The next two photos shows the soil wearing away
And this is what it looks like today!