Wikipedia
Moricons.dll is a dynamic-link library file containing icons.
The file was first distributed with Windows 3.0 and contained the icons for launching many popular DOS applications of the time, such as WordPerfect and Lotus 123. Windows setup included the option of searching the local drives for compatible DOS applications and if found, would create an item in Program Manager under the Applications program group, with an appropriate icon from the file.
moricons.dll was found in %SystemRoot%\System\moricons.dll on DOS based Windows installations, from Windows 3.0 to Windows Me.
On Windows NT based systems, including Windows XP, the file can be found in %SystemRoot%\System32\moricons.dll.
Although all but deprecated, with modern Microsoft Operating System compatible applications being Windows based. However, the file may be useful in giving a user created application or shortcut a custom icon.