Dark colored formation of objects traveling from the south to north just north of Seattle. (APR 15 21:10:16PM)

I am interested in the subject of  UFO/UAPs and consistently look up to try to catch something. This is the first time I have seen any thing odd that I couldn't really shrug off.
 This occurred Thursday April 15 2021 @ about 10:16 PM.
I was taking my dog out for the last time before bed,  The weather in western Washington has been beautiful the past few days.  I look up at the stars as I always try to do if it is clear. I noticed a formation of objects , I think 6 in total but I cant recall exactly because it happened so quickly.
There were 4 objects in a line and 2 off to the side. The formation was moving in a south to north direction.
They were a dark gray color against the dark navy blue sky. They were very hard to see, but they had zero deviation in the individual objects shape and the formation.
No lights at all, no sound, my dog did not notice anything.
 They seemed to be much lower than satellites, and planes often fly in the airspace waiting to land at SeaTac airport... but these had no lights at all and no sound.
I will send a quick sketch to help visualize.