This is how I would do on my side :
Draw a disk in the top view.
Select all the surfaces and combine them.
Draw a line to make the horn shape (something curved ...).
Extrude the disk along the line path with scaling (10%).
You can find the "Extrude along a path with scaling" plugin on Dennis website :
http://www.supercoldmilk.com/ac3dplu...ath_scale.html
HTH.