Brown spots on bath bomb

[angel1]

Hi can anyone tell me what would cause brown spots in between the bathbomb base and my cupcake topping? I'm not sure if its mould spots or not? In the image below as reference, they would appear just around the level of the top of the cake holder, in between the two different parts.

 

[Hazel]

I'm bumping this so maybe somebody who has an answer will see it.

If you had said it all discolored brown, I would have thought it was the FO but I don't know what would just cause spots.

 

[tinytreats]

Funny that I read this today, because I noticed just yesterday that I have the same brown spots on my bath bomb cupcakes in between the icing and the bath bomb. Honestly, I don't know what it is. But I think it has to do with the FO. Have you used the same FO in anything else? Have you noticed any discoloration with it? I also thought maybe it could be any retained moisture from the bomb coming out the top? Or maybe the icing has been "sweating" and reacting with the bath bomb? Is your soap icing the Royal Icing or is it whipped soap? If it's soap, did you use melt and pour? Maybe you heated the melt and pour too hot and it started to sweat?