Which cells are considered immortal?

What do animals wth echolocation have in common other than echolocation

Natalie had random hand movements when she was two months old. when she was six months old, she used to grab a block with her whole hand. now at the age of ten months, she can grasp the same block with her thumb and forefinger. this sequence of growth in her hand and finger movements is according to the pattern.

Explain the significance of the increased cell specialization of the volvocine line