it is a Astrea Snail. I have 25 of them. I dont think the Algae moves on its own. I have only seen it on the one snail . It is basically black with a white bubble type tip...
Is it bad?
The black algae is sitting in a circular pattern on the snail's shell...
then the white spot is sitting dead center on top of the black algae..
I dont even know if it is algae?