Energy Ball by Digital Smith

This is a cool one. In fact all four of your filters so far are pretty interesting.

This is very cool, I have been working on something similar. Only complaint is the horizontal black lines...?

Very..

Is it possible to have a complete transparent background? So that I can place it as a new layer in (for example) photoshop

I really like this filter!!!

Paul, if you haven't figured it out by now, just turn seamless tiling on and the boundary will go away. Seamless tiling can affect more than the four edges of the image, depending on the filter.

Seamless tiling is needed because... technically, because there is a noise leading into a coordinate transform, specifically Cell Noise leading to a Polar-to-Cartesian transform. Sorry if that doesn't make any sense.

I think you are right about Spherical Displacement, that it should have seamless tiling enabled. It is convenient for us if you link to a library filter if you mention it, like I did, so we don't get confused between filters.

If seamless tiling is disabled for a filter, then you can enable it by opening the filter editor, then clicking Filter -> Overrides -> Seamless Tiling and setting it to "enabled" (you still have to check the box). You can't do this with the Basic edition of FF.