After Effects - What is this icon on the layer?

[Onvibe]

What is the icon below?

How do I add or remove it from a layer?

  

[jane-e]

@Onvibe 

I've moved your post to After Effects where you are more likely to get help.

Jane

[nishu_kush]

The icon shows that Track Matt is applied on the layer. You can read more about it here. 

Feel free to reach out if there are any other questions.

Thanks,

Nishu