Those were built in IC mounted directly into a small PCB for a mass faster production to save labour cost.
Its design can be any function depending from the manufacture requirement .
If it really is part of an IC and it's round (and without a photo of any kind), I'll guess that what you're referring to is encapsulation (potting) compound placed over a proprietary device to discourage tampering or reverse engineering.
I second Roger's answer, Chip-On-Board. Silicon chip soldered directly to a PC board, then covered with a drop of epoxy.
That is called Chip On Board (COB)
https://www.google.com/search?q=chip+on+...
IC stands for Integrated Circuit. It consists of one or more circuits designed for certain function.
They comes in as a finished product so that it can be mounted with ease.
Often found in toys, remote controls and calculators, the chips are small, round dollip shaped packages. I call them tear drop ICs because they look like a bead of water
