If I learned right earlier today, that is a chip formed from the crack. It has to be pretty large to be a "retained cud". Please, anyone, correct me if I goofed.
I goofed on the retained cud part! Cuds must connect to the rim. Here is a good link http://cuds-on-coins.com/die-chips/
Looks like you are learning! I wouldn't call this a retained cud because the two die cracks do not intersect.
I'm not a error coin expert but I think what you have is called a Retained Interior Die Break. https://cuds-on-coins.com/retained-interior-die-breaks/ A couple of experts are @paddyman98; @Fred Weinberg; @furryfrog02; @desertgem; @JCro57; et al. According to this site it could be a freestanding IDB http://www.error-ref.com/retained-interior-die-break/