IUD STRINGS?

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Can iud strings break off? I looked in the toilet today and noticed a black wire like thing, it was pretty thin and about 2 inches long. I just got my iud checked up on 2 days ago. I have Kyleena and I know the strings are blue so when they soften do they turn black? Do you think it’s my IUD string or something else? It was in a public restroom so who knows. Lmk!