Biogenic guanine crystal (GC) is abundantly contained in fish scales. This crystal has thin plate form and high light reflectance with the largest plane of it. Effects of magnetic fields on GC, which shows diamagnetic orientation were investigated in our previous studies. In this paper, we tried to apply the biogenic crystals to micro algae culture for the purpose of acceleration of the micro algae's photonic synthesis. Recently, micro algae were focused on the view of producing bio-ethanol or bio-fuel. In particular, crystals, which have high refractive index and contain nitrogen in their molecule, seem be to available for one of fertilizer for plants. In addition, crystals, which have high refractive index, reflect light well, so we expect that these properties help algae's photonic synthesis. Additionally, some algae have the photo-tactic characteristics, phototaxis. Therefore, we also aim to utilize these crystals for efficient culturing of algae. In this paper, microscopic observations of behaviors of the micro algae in the cell culture chamber with a buffer containing the crystals were carried out. We tried controlling of alga motions with directive light stimulation from magnetically aligned biogenic GCs.