What is this part of the webcam called?

This is basically a complete camera sensor & lens assembly in a single SMD component. Sparkfun use to sell something like this here - SEN8667

The part that you unscrewed was likely used to focus the lens, although these styles of cameras basically have everything in view in focus (Based on sensor size, focal length & aperture). Below you can see how the DOF changes as the aperture is increased (Aperture Hole size decreased). This style of camera basically has a fixed apature & focal length so the exposure adjustment is all done in software via shutter speed & ISO (Gain) adjustment.

The closest thing I can find to this that can be purchased by consumers is the OV2640 this is the same style component but attached to a small PCB ribbon cable. These are used on raspberry Pi's & the ESP-Cam modules.

This sort of component would be hard to get your hands on unless you are planning to buy in volume direct from a supplier especially in the surface mount component style.

They're often called "board lenses". They can be either integrated in with the sensor, or interchangeable. The interchangeable ones are usually "M12":

http://www.m12lenses.com/Board-Lenses-s/12.htm

Usually devices with an autofocus will not have interchangeable lenses (since the lens is mounted on a voice coil driver). In your case, it looks to me like the lens is custom for the sensor and probably not something you will find a datasheet for.