An essential tool for ikebana
(Japanese flower arranging
They come in many different shapes and sizes, from only as large as the end of one's thumb to large enough to hold a pine bough.
A kenzan consists of a flat metal base with a large number of thick pins that will hold the stem of a flower or branch at the precise angle intended.
I have heard that these are sometimes called "frogs" in the West for some mysterious Occidental reason.