Is this mushroom or animal? I can remove the black dots by slightly scratching the leaves.
If you can remove them from the leave then they are scale. Due to the dark colour I believe they are Black Scale (Saissetia oleae). They suck juices from the plant and excrete a sugary sap. Look for sticky leaves. Ants are sometimes seen in close company with these pests.
For small plants some control can be done with soap and water but a complete answer is here.
Edit @RockScience feels they are a different species of scale for which a reference can be found here. Either way soap and water and possibly a toothbrush for "hands on" pest control will work.