I think the Unknown sales today in the "black" column on L2 were buys/sells made in between the buy and the ask.
IMO, someone using a brokerage that allows them to buy and sell at the 4th decimal is making a killing...
This could be further evidenced by the "fat finger" that they forgot to leave out of the trading today and went through as a T-Trade should have been a .00035 buy....