Reframe Japan, Wabi-Sabi

Shikamaia ( シカマイア )

Permian period

In a geological age called the Permian period which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago (Mya), to the beginning of the Triassic period 251.902 Mya, the world at the time was dominated by two continents known as Pangea and Siberia, surrounded by a global ocean called Panthalassa.

World Map

During the Permian, all the Earth's major landmasses were collected into a single supercontinent, Pangea. Pangea straddled the equator and extended toward the poles, with a corresponding effect on ocean currents in the single great ocean ("Panthalassa", the "universal sea"), and the Paleo-Tethys Ocean, a large ocean that existed between Asia and Gondwana.

Sea levels in the Permian remained generally low, and near-shore environments were reduced as almost all major landmasses collected into a single continent - Pangea. This could have in part caused the widespread extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms.

But besides that, the Permian (along with the Paleozoic) ended with the Permian-Triassic extinction event, the largest mass extinction in Earth's history, in which nearly 96% of marine species and 70% of terrestrial species died out.

The cause of the Permian-Triassic extinction event is still unknown. Many scientists argue that the Permian?Triassic extinction event was caused by a combination of some or all of the hypotheses and other factors; the formation of Pangaea decreased the number of coastal habitats and may have contributed to the extinction of many clades.


In the Permian, there is the largest bivalve in the Paleo-Tethys Ocean. The name is Shikamaia and its size is considered more than 1m(3feet).

The first individual(fossil) was found in Kanabuyama which is considered as the birth place of palaeontology in Japan in Gifu prefecture. It is considered to live in symbiosis with photosynthetic dinoflagellates (zooxanthellae) same as giant clams (Tridacninae), however, nobody know what exactly it is since mollusk portion is not left in fossil.

Giant clams, シャコ貝

During the Edo period, there is Shukuba refers to urban areas that were established mainly along the Go-kaido Road (Edo Five Routes) and Wakiokan (secondary route that connected the Five Routes) to look after officers who transported luggage from one post station to another. Akasaka-juku (Nakasendo) which is one of the Shukuba was prosperous by lime and marbles from Kanabuyama. So, from Edo, Akasaka-jyuku which is located in the present day city of Ogaki was developed by the marble industry. The marble industry was famous all over the country in Japan, however, it is in decline.

However, one lineage tree is there.

Since Kanabuyama and Neo area have a discriminating geological strata with limestone area, Shikamaia is found in both place. And a ball of Shikamaia is sold in the following site:

Shikamaia, シカマイア

Since several individuals are folded, piled up in layers and compressed, it may be difficult to identify what portion of Sikamaia is seen in the ball. However, Sikamaia ball excites our spirit of romantic imagination.

As a lucky charm

Bivalves such as clams would not match any shell other than their counterpart, so people played kaiawase choosing a pair out of the shells placed face down. Kaiawase (or kaioi) is a game played during the Heian period pairing the two pieces of a clamshell in Japan.

Because the shells did not change their partner, they became a symbol of conjugal harmony. Therefore, Kuge (court noble) and Daimyo (feudal lord) family prepared beautiful Kaioke(a kind of bucket used to keep clamshells) and shells for their daughter as the bride's household articles.

Although bride's household is not popular in present day, Shikamaia ball might be one since it is the largest bivalve.

Kaiawase, 貝合わせ