Do you mean the shock mount?

It's designed to hold the mic and avoid transmitting vibrations from the mic stand (caused by moving or jostling the stand) to the mic.

https://i.ebayimg.com/images/g/dwEAAOSwg0deXHFG/s-l640.jpg

It’s a shock mount (probably [1]), meant to reduce noise transmitted from the table or the boom arm or whatever the microphone is attached to.

[1] https://en-de.neumann.com/ea-87

That's a shock mount - it prevents vibration on the mic stand from being picked up by the microphone.

It's a shock mount system. Suspends the mic from any external vibrations