I bought a crate of Lego's from a flea market, and it has this strange block inside it. It's a transparent blue color, round, and somewhat thick. It seems to be a single piece, I can't find anywhere to separate it. It has wiring inside of an unknown purpose, and I can't see anywhere to connect to the wiring, so I am assuming it's some kind of wireless thing, but I can't imagine to what end. There are at least 3 of them that I have found so far, and they all have different numbers on them -
16R5, and some smaller numbers that I couldn't quite make out. There is a shallow circle hole on the bottom, but it's just barely too small for a normal brick "dot" to fit into.
I'm curious what these are for, and what set they might have come with.