Bests & Worsts Reviews from Amazon

Parents, please be aware. Our 7 month had this for about two weeks with normal play - picking up, licking, attempting to eat it, etc. We noticed today a black residue on his mat. Took a minute to realize it came from this toy. If you look at the pictures closely, then you'll see the residue all around the center rim. I decided to open it (okay I tore it open instead) and found the source - the black magnet (or whatever it is). Not sure if anyone else encountered this or it's a one off situation, but wanted parents to know. Luckily my son did not ingest any of this.