Period 16284 Agar
Nicolay Beluchenko has found a B-Heptomino based agar. A 14 x 23 array takes 354 generations for the array to reappear shifted 6 cells and flipped horizontally. 708 generations are needed for an unflipped version to reappear shifted 12 cells vertically but none horizontally. The array will reappear in its initial position and orientations after 16,284 generations.
Edge stabilizers to convert this agar into a bounded oscillator is left as an exercise for the student.