A UFO!

That is, an Unidentified Fungal Object.  It looks a lot like melting candle wax to me.  It might be a Lion's Mane fungi, at least the beginning of one, which are often seen in Maine.  Doing a bit of reading on it, it is said to have nerve regenerating properties and shows some prospects as a treatment for dementia.  How interesting!  You just never know what you will find growing on an old tree.  Nature is just full of surprises.