What does this icon mean in ArcCatalog?

[JerryGarcia]

What does this icon mean in ArcCatalog?  See attached picture.

I do not see it referenced in this article:

FAQ: What do the icons in ArcCatalog represent?

http://support.esri.com/technical-article/000006049

When I click on it, it turns into the "polygon" feature class icon, which is what I would expect to see since it is a polygon feature class. 

Why does ArcCatalog do this?

The data is stored in SQL Server.

Thanks!

[JoshuaBixby · Accepted solution]

See View data from a database in ArcGIS.

Tables that contain a spatial column (feature classes) have a table icon with a square at the bottom .

In your case, from the small image you uploaded, it seems you are working with a geodatabase.  If you have tables in your geodatabase with spatial columns, but those tables weren't loaded using Esri's tool, the don't get registered with the geodatabase.  Since ArcGIS for Desktop can work with several databases' native spatial types, the software can see the tables and tell they have a spatial column, even if not registered with the geodatabase.

[JerryGarcia]

Thanks!