All Octicons
file-submodule
Octicon sizes navigation
React
import {FileSubmoduleIcon} from '@primer/octicons-react' <FileSubmoduleIcon size={16} />
Rails
<%= render(Primer::Beta::Octicon.new(:"file-submodule", size: :small)) %>
Jekyll
{% octicon file-submodule height:16 %}
Figma
This icon is called file-submodule
in Primer's Octicons library.