Any help identifying coin?

Hi, I found a coin in my grandfathers coin collection that I have trouble identifying. The metal is quite light, about 3 grams on the kitchen scale, thickness is 1,5 mm and diameter is 21 mm. There is no inscription or anything on the sides, those are completely smooth. One side seems to have something like a cross and flower petals, the other sides has lines, but I can't discern any writing. Has anyone seen a coin like this before?

Hi! No,I haven't seen a coin like yours but the cross & quite something of the coin's style tell me that it may be a middle-ages Spanish coin,before the 16-th. century. More,I can't say…

Andi

 It is NOT a coin. 

No country. No date. No lettering. And so on. 

Yes, I already stumbled on the Spanish angle, for me it looked like a real or patagon, or something like it, but without the edges of the coin, so only a part of the coat of arms and the cross on the back with the petals around it. And of course quite worn away and abraded. This would explain why there is no writing on the coin. I found these examples in the database. 

My friend Snoodvark,without been very sure that this is the right answer for your (coin),I wish to tell you that for the middle-ages Spanish coinage is quite usual to find fragments of original complete coins,used on markets for payments. These are the so-called COB COINS,sometimes only the genuine center of the original coin remains. Is your coin made of silver? Usually,''cobs'' are. 

I also can't reject completely the other member's opinion that maybe it is not a coin… Especially if it is not silver or copper(sometimes).

Andi 

P.S.: There is something else VERY strange for a ''cob coin'': it is too round! ; ''cobs'' are not so perfect,far from this…

OK, I'll look up cob coins, thanks! I have no idea whether it's silver, it is very light. I'll look into how I can determine what material it's made of. 

Looks like a fantasy piece or “pirate treasure coin” trying to imitate 16th-17th century Spanish colonial.

It is too round to be authentic, the design is amateurishly wrought, and there are no inscriptions (as pointed out by ZacUK)

Hi! Oh yes,tdziemia,you may have expressed the last answer with ''a fantasy,imitative of Spanish colonial coins''(like those ''pirate treasures'' coins). I didn't think of that! You also noticed,like me,the shape much too round for a supposed ''cob''(much irregular in shape). 

I wish a fine day to all of you!

Andi 

P.S.: And if the metal is not silver,then the ''solution'' with a ''pirate treasure imitative coin'' is the best & the right one.