In TeXForm#
TeXForm parses this entry as a character leaf mapped to U+21C3 (DOWNWARDS HARPOON WITH BARB LEFTWARDS).
\to\rightarrow\longrightarrow\mapsto\xrightarrow\Rightarrow\Leftrightarrow\leftarrow\longmapsto\hookrightarrow\Longrightarrow\downharpoonleft