@Simon Bacteria Model

I've been trying to model my bacteria but I have no clue how to make the mouth, I've tried deleting faces and bridging them together or using extrude and it hasn't worked well. I've also tried avoiding deleting faces and just adding edges but it only adds on one side of the model so I'm unsure how to go about this. Any advice would be greatly appreciated because I'm becoming quite frustrated with this. I started with a polygon sphere and I've also tried it with a cube to see if it works better but it doesn't. I'm sure it's something simple but for some reason I can't wrap my brain around making a mouth so I think I just need some guidance/help.

***Update***

I decided to give it another go using a cylinder and I tried deleting faces, extruding then I merged the edges (I think I did at least). It seems like it worked ok...so I figured I'd post a bunch of images to be sure.