Crispy coated chocolate buttons that you tried to leave on your tongue to melt.
Chocolate Treets, made by Mars, were very popular. there were toffee, peanut and chocolate versions. The chocolate version was flat with a hard shell and chocolate centre. They were re-named Minstrels and still exist. The toffee flavour and peanut flavour were round, had a hard shell coating and a chocolate and toffee or chocolate and peanut centre.
They were discontinued, although some people say the peanut ones were coloured and re-packaged as M&Ms. I think they taste completely different.