Growth in plant is totally different from the animal growth as growth in plant is unlimited and indefinite. Root and shoot in tips in the plants are open ended i.e. they always grow and form new organ to replace the older and senescent one due to presence of meristem cells, which are capable to grow and divide. Thus, the plant growth continues throughout the life. On the contrary, animal growth is limited as growth /stops as soon as they mature. Sponges are those animals which show cellular level of organisation. These animals posses totipotent cells which are capable of giving rise to all other cells in sponges. A small part detached from a sponge can regenerate into a whole new sponge. However growth in sponges cannot be called open or indefinite as they cannot grow beyond a certain size. Practically, they do not show open ended growth.