black specks on leaves
I'm new to the forum but have been making bottled terrariums for a few years now. This is my third and largest one and hasn't been watered for about a year and a half. The soil does a good job of staying moist from the condensation which occurs about twice a day.
There are two varietys growing inside. Recently I noticed black specks on most of the leaves of one of the plants. I'll try to upload an image here. Any thoughts on what's causing this, if it is harmful or not, and what to do about it?