I just noticed today that our Crimson King maple has a 5-7 foot split on the south side of the trunk. The tree was planted about 10 years ago. There is a very wet two foot section where it looks like water is running down the trunk and that section's bark appears to be decomposing - the bark has turned to mush (maybe from being so wet). I saw a couple bugs in that area and there are a lot of small ants (not carpenters) running all around the trunk. There is a lot of moss located all over the trunk. No branches were lost recently and the tree appears to be healthy, with no thinning on the south side. The last time that we fertilized was probably one or two years after it was planted. I attached two photos of this tree.

Our second Crimson King also has a lot of moss and ants crawling through it. I also noticed a few red patches across the trunk. I attached one photo of this tree.