Planaria is a common flatworm, part of a species that you might find in your local pond or stream.
-- Planaria have a special weapon. When it sees food, it shoots a tube out from its throat to hold its prey down. Then enzymes that come from its throat softens the tissue. That makes it easier for to tear apart pieces of the prey into microscopic bits.
-- These flatworms can also regenerate. Well, all creatures can, to some degree, heal themselves if they're hurt. The skin of a human can heal for example. A salamander can replace a limb. A lizard can replace its tail. Earthworms can sometimes replace one or the other end of its body -- but it all depends on the health of the worm and where the break is. But for planaria, it's easy. In fact, they can replace a head, a tail, and can grow many heads and/or many tails.
-- There are even some kinds of planaria which can regenerate complete worms from almost any piece of their bodies. Of course, those guys are of great interest to scientists.
-- Where do planaria hang out? Under rocks, streams, ponds. Sometimes people tie a string to a piece of raw meat and throw it in the water and whistle. If planaria is around, they'll come.