Here's a new one, the coins that hurt your brain to ID and/or date

  This one is pure newbie, the Iran 250 rials KM# 1262. I thought the blossom looked like Bangladesh national emblem. So had a hard time getting past Bangladesh.

 The next one that got me for some time, before finding Numista, is Austro-Hungarian krone


 The next is Malay peninsula tin coins
  

 And the hardest to date have to be Tibet 1 sho coins


 And of course cash coins. Still lost out at sea with them
          yours daryl

The hardest ones to date would definitely be the Spanish coins with the miniscule numbers inside the stars.

I forgot about those; yes they are a pain.

Coins from Thailand are my bane.  All of the squiggles look the same to me!

And the squiggles are differenced from coin to coin . Just a little.

The poor striking quality and chaotic mintmarks make collecting modern Indian coins a real headache!

For Austria-Hungary it is relatively easy (specially if you know some basic heraldry): the red-silver-red arms on the chest of an Eagle (double-headed: looking to both Germany and Russia for guarding) are always Austrian.
7 times cut red-silver fields (horizontally) are always Hungarian (so is the Madonna with child)