Neat but not true. Many jelly fish can revert to an embryonic stage at will up to sexual maturity. Only one known one, Turritopsis nutricula, can do this at any age. As an embryo however they are easy prey and may still die from predation. Lobsters do age, their cells just don't show signs of it like most creatures. A lobster keeps growing it's whole life instead of stopping like most creatures, and can regenerate lost limbs and maintain it physical abilities at almost prime levels into old age. They will eventually die of complications related to aging though, like most other creatures.
"Oh, I wanna be a lobster!"