Try staring into the abyss on your free time; you get a little less lonely when it stares back.

For more creative options to generate from the Curve section, you can activate the Add Curve: Extra Objects add-on. The SpiroFit.

Most objects in Blender can be equipped with Force Fields, simulators of 3D physics. They can simulate many types of physical phenomena, but for today's study, the main topic is on the default mode Force.

In a nutshell, the default Force Field acts like a source of gravity that either attracts or repels. Controlling whether it pulls or pushes is simple: scale the Field strength setting to a positive value for attraction and a negative for repulsion. As for the Flow setting, increasing it limits the scatteredness of its gravitational ability - for example, creating a wind barrier preventing Metaball piles from splattering outward the broad 3D space.

So far, you have your trail of Metaball sludge, but do you agree they look a bit… blocky? If you concur, select your original Metaball object. At the MBall section, you need only decrease its size on Resolution or Render to further smoothen them.

Note to self: bake your complex animations before rendering them! Otherwise, suffer resetting Emitter path nodes across the animation process!

Instead of simply making a mercury spiral, do try having fun with experiments on Metaballs and Force Fields!