It is a pen that can draw the microorganisms in the petri dish like that. シャーレの中の微生物がそれっぽく描けるペンです。

It is easier to draw the nucleus with a small pen tip and then cover it with a large pen tip.

小さいペン先で核を描いた後大きいペン先で被せるように描くと楽です。
It is a pen that can draw the microorganisms in the petri dish like that. シャーレの中の微生物がそれっぽく描けるペンです。