Some Arab Coin

I found a old coin in very bad condition. 

All I can read is Turkey, oman, Dublin and some Arab text.

I can't find coin value or name for it

 What is the diameter? 

It is a coin from Oman, and is one of these > 

https://en.numista.com/catalogue/index.php?e=oman_section&r=&ct=coin&im1=&im2=&tb=y&tc=y&tn=y&tp=y&tt=y&cat=y&ru=&ca=6&no=&v=&i=TURK*&b=&d=&u=&a=&dg=&m=&f=&t=&w=&mt=&g=&se=&c=&wi=&sw= 

Lettering: FESSUL BIN TURKIE IMAM OF MUSCAT AND OMAN 

 I added (in red) the visible letters and all those match that lettering > 

 Red= certain, Yellow = probable, Green = guess