From The Aquarium Wiki
An Iwagumi styled aquarium (also called Ishigumi Style) is based on a Japanese term for a collection of stones or rocks arranged in an aesthetic appearance in a garden.
Iwagumi literally means "rock formation".
Typically the grouping of one large stone with two smaller stones that lean toward the central stone.
Together with planting and fence design, lwagumi or ishigumi is one of the three major aspects of Japanese gardens. Three-part ishigumi typically feature a central stone (shuseki) and two subordinate stones (soe-ishi).
Common types of stone arrangements
- Hourai ishigumi, shumisenshiki ishigumi, sanzonshiki ishigumi, tsurukame ishigumi, gogan ishigumi, hashi-ishigumi, shichigosan ishigumi or renzan.
- Sanzon-Iwagumi - Buddhist triad stone arrangement. Large stone with 2 smaller stones in a triangle.