Though shield showed owner's position and a social position.
It was used for the decoration as well with the change in the age.
It came to add various accessories one after another.
But, those accessories were not mere decoration, but a position. social position made them the structure that it had a look and which could be distinguished by the shape. color. and so on.
The crest which accessories were stuck to was distinguished from the crest of only shield
In English, (Heraldicachievement). With the slang (Greatarms).
In French (Armories).
It is called (GrossWappen) in German.

Crest	Torse	Badge	Helmet
Escucheon	Mantlin	Supporter	Scroll

Crest
There is an element which is the same as the Japanese family crest in this part.
It is the same as the ornament in the Japanese armor.
The same family can use it.
The crest can't be used for the woman who doesn't participate in the battle, and the churchman to do the origin in the helmet for the actual fighting.

As for the European crest, it is one characteristic to be various from the viewpoint of object as for the Japanese family crest.
tincture
metals
colours
furs
Three are divided into the group.
When a primary color is used, a neutral color and pastel color can't be used.
A metal color can't be used for the metal color.
There is a rule of 9-11point in field of others shield.

「heraldry for the designer」  William Metzig  Bijyutusyupan1971.3.20