The traditional astronomical symbol for 10 Hygiea, after Gould, B.A. 1852, On the Symbolic Notation of the Asteroids, Astron. J., 2, 80. As the number of asteroids grew, the symbols got more and more complex, leading to the creation of minor planet numbers. This one is perhaps the most complex of the symbols at the time Gould made his proposal: a Rod of Asclepius.
Own work
This file by Editor at Large, original image by Adam Cuerden