In traditional Japanese culture, suiseki (水石) are small naturally occurring or shaped rocks which are appreciated for their aesthetic or decorative value. 
They for fill the same emotional essence as bonsai trees , you get transported to the mountain top. 
Much sought after in Japan , The history of suiseki in Japan begins during the reign of Empress Suiko. The small objects were brought to Japan as gifts from the Chinese Imperial court.(Empress Suiko (推古天皇, Suiko- Tenno ) (554 – 15 April 628)

According to Hideo Marushima (丸島秀夫, Marushima Hideo, 1934- ) in The History of Suiseki in Japan (日本愛石史, Nihon aisekishi),

It is not a silly thing at all to enjoy a stone in a tray. I see the whole world in a tiny stone. Some objects in this world are huge, and others are small, and they come in all shapes, but they are not that different when you look at their essence.

Popular types of suiseki suggest a mountain, a waterfall a island, in-fact most of the natural world .