Sentence:  I was looking at a 151 mm caliber cannon, which used the twentyfour pound cannon ball and displayed a beautiful lion′s head on the back end of its breach area. An elaborate <WSD>cascabel</WSD> stuck out of the mouth of each animal. The <WSD>cascabel</WSD> was primarily used to attach ropes that secured the cannon during the recoil blowback that came from firing. 
Meaning of the word marked with <WSD> tags:  A knob at the end of a cannon, cast onto the gun barrel, to which ropes are attached in order to control recoil.