Another varient of mystery Latin symbol for 'reverse'

We previously discussed Eckhel's decorative symbol for reverse, which looks something like a cross between an asterisk and )(.

Notitia elementaris numismatum antiquorum ... (1758), by Erasmus Fröhlich, uses a similar symbol.



The symbol can be seen in context on page 21. Like Eckhel, sometimes )( is used instead, such as on page 73.

I'd really like to learn what the symbol is called, and why it came to represent the reverse of a coin.

I spotted a 20th century use of the )( form, in Haeberlin's Aes Grave (1910). So use of the symbol died out less than 100 years ago. Aes Grave is in German, so it's another non-Latin usage of the symbol.