Fragmentation in multicellular or colonial organisms is a form of asexual reproduction where an organism is split into fragments. Each of these fragments develop into mature, fully grown individuals that are clones of the original organism.
The splitting may or may not be intentional. It may occur due to man-made or natural damage by the environment or predators. This kind of organism may develop specific organs or zones that may be shed or easily broken off. If the splitting occurs without the prior preparation of the organism, both fragments must be able to regenerate the complete organism for it to function as reproduction.
Fragmentation as a method of reproduction is seen in many organisms such as cyanobacteria, molds, lichens, many plants, and animals like sponges, flatworms, some annelid worms, and sea stars.
Sea star regeneration
The information on this short video clip isn't too bad.