Need help with a tutorial I saw, identifying a tool from the icon used

[wanderers005]

Hey, brand new to Maya, so was watching a tutorial on YT, but the person doesn't explain what tool they're using very well. Can someone please tell me what tool this is, based on the icon? Thanks.

[hamsterHamster]

It is not commonly used or even might be 3rd party, so go figure.

Post the link to the tut, or at least give the background in what context it is used.