Trick worms fall slowly and can be worked weightless near the surface but don't actually float. Roboworms are an example that actually float. Some worms have air pockets or differen material that makes the tail float. I like the Kicker Fish Hole Shot worm - the tail floats up. There is a YouTube video where several baits are compared in an aquarium - don't remember site but shouldn't be hard to find.
In memory of my childhood friend Dan Sterling, who taught me at an early age how to catch bream with a hand-line, and who unknowingly hooked me on fishing for life.