Lemon, most likely not, I am amateur of this... dinoflagellate algae cell has a flagellum tail for propelling itself through water.. And the pics shown by Bro Onizuka is most likely Cyno... it could be the effect of long age cyno which the photosynthesis in round end form...
And for dinoflagellate algae, silicate is not one of its needs as is the case with diatoms. Unfortunately calcium carbonate is. Above statement extracted from "Marine Algae Control Secrets by Bob Goemans"
Do you have you algae outbreak pics to share? is it look like below?
Thanks...