Found in Davis Square: a bicycle light.   Normally these found posts ask people to PM with identifying info to confirm the keys/phone/etc is actually theirs.   In this case, it is somewhat generic non customized product, but if you lost a bike light at least PM with the brand/model and any comments on where you think you might have lost it.

Bonus points to the first person to point out the irony of this posting vis a vis the other recent bicycle light posting.