The gravity sim would have to be slowed down and made "looser" to get the floaty effect of cells in liquid though.
The way to this would be, either to change the constant at the start of the set velocity equations, or to (increase that and) raise the power of the distance formula. So for example:
instead of the formula being a=Gm/r^2 it's a=Gm/r^3(or more) where G is a constant m is the mass of the sprite it's being attracted to and r is the distance.
The effect of this would be that when the sprites are far away the force is lower, and when they're closer the force is higher. In fact this is why what you were doing before was really weird, the force of attraction was actually higher when they were far away.
I was thinking more along the lines of gRAVTARDEROIDZZZZZZ... but yeah whatever
The other issue with it is it would be nice to have tons of asteroids, but this isn't feasible with it having a loop with (number of objects)^2 iterations, I'm sure something could be done to make this better, such as adding a "pick by distance<200" or something between the two loop conditions. Though this might cause other issues (like them not attracting far away )
One other thing I thought would be cool (and briefly tried, failing horribly) would be to somehow treat all the clumps as one object, then shove a big bubble or something on top of it, using mesh distortion to give it the shape. This is probably too insanely difficult though, I couldn't make it work out which clump was which at all.