What is he feeling??

Okay so last night me and my husband were having sex and he said he could feel something like he was hitting something in there... well I didn’t understand because I didn’t know wth it could be I’m 25 weeks pregnant but I’m 99% sure he isn’t hitting our baby😂😂 so I was just wondering if anyone else that’s pregnant has had this happen or knows what it could be. (He said he’s never felt it before)