Luminaria pose an interesting problem for musicians compared to the other Electroplankton. First, they are the only exhibit with a definite beat but no way to change the tempo. Luminaria tunes must all run at the same speed. It's really too bad, because this is probably the busiest and most musical of the plankton types, and by far they are the most accessible. Luminaria are well suited to fill in background space, since they basically generate cyclical chord patterns in the key of Bb major.
Speaking of the grid, it's a 6 by 6 space composed of arrows, each aiming a plankton to one of the eight surrounding grid points. The arrows will wrap the screen on all four sides, so a plankton can exit left and enter right, for example. Arrows can be set manually by tapping on them, in which case they'll increment clockwise with each tap, or they can be set to spin automatically with the 16th notes by holding the stylus on them. The latter basically creates a random effect, but since the spin is regular (completing two full spins each measure) it can be predictable. You can use the randomness to sort the plankton across overlapping paths, since they'll hit it at different times, but since it is hard to time precisely, you won't necessarily know which plankton will end up on which path.
It's also possible to adjust the arrow pattern with the d-pad. Up and down will cycle through set patterns that may be useful, although they may change the time signature, since the paths change lowest common denominator. Left and right will align all the arrows in the same direction, starting pointed up. Arrows set to spin automatically will not change with the rest, but will keep on spinning. The arrows will remember their last aligned state shift and base their mass rotation on that, ignoring all other changes and set patterns made since the last left/right press.
As I've said, Luminaria are tuned to Bb (which makes them well suited for band and orchestral instruments, particularly clarinets and other woodwinds in the key of Bb or Eb). There are five octaves contained in the note grid, with the lowest in the upper left and highest in the lower right. They increase in pitch reading left to right, just like text. The following table details the pitch of each grid point. I've colored the starting points for each plankton.
I should note that because of the locked rhythm, defined key, and easily-abused set patterns, Luminaria compositions will tend to sound very similar. Using manual, point-by-point settings will help avoid this tendency, as will active involvement in the paths for the plankton. Remember that you don't have to use all four at one time, and grid spaces can be occupied by multiple moving and stationary plankton--use the d-pad to shift arrows underneath the corners if necessary. Setting up new paths for the plankton manually before you start them off will also break up the monotony.
Next up in the series: I plan to explain the contrast between Rec-Rec and Beatnes for sequencing and drum patterns. I'd also like to talk about hard-to-use plankton, such as Tracy and Lumiloop, and their role as musical accents.