These are arrowhead plants which are grown for chinese new year. Need to change water regularly so as not to breed mosquitoes.
It took about one month for them to grow to this height. It's attractive, jade green arrow-shaped leaves point skywards and to the Chinese, this is an auspicious sign as it signifies continuous improvement . To read more about this you can read from the source in here.
Marbles or pebbles are added so that the plant will be stablised and not fall off.
Do you remember my previous post on this cactus plant? Well, it had given birth to more baby cactus...lol. You might want to see my previous photo of the pair of cactus in here.