Ancient coin identification

This coin came with uncleaned late roman coins. It appears to be Celtic but I am challenged to identify. Any ideas?

I see that this is your first post here, the forum is split into multiple parts where you start different types of threads. You posted this question in the free discussion part, where people mostly just chitchat, when you really should’ve posted in the identifications and evaluations part where, well, it says in the title what should be posted there.

Everyone makes mistakes, and you’ll learn where to post things with time, hope to see you more on the forum from now on! (on the right parts that is 😄)

@ZacUK 

 What is on the reverse / what is the diameter? 

Picture cropped …