I wonder if it's because we only see that particular bit of the tree that makes it so easy to spot these shapes ! Perhaps it is your imagination in the first place making it easy for us ! Whatever ...it works !!
Since Rick (@digitalrn) posted a photo with the woodcreatures tag, I just had to check yours out. Love this one. Looks like a dragon to me. Very cool find. Now I'll have to be on the lookout for wood creatures.