From Blue-IT.org Wiki

Because I did not find any icons for my beloved ICONIX process, i made some.

Here they are (96x96 pixel), feel free to use: for private use or any other!

Uml 96x96 boundary.png

Uml 96x96 control.png

Uml 96x96 entity.png

And here the gimp file: Entity control boundary.xcf