Proto-writing happened over an extensive area over thousands of years. While proto-writing developed into “proto-cuneiform” in modern-day Iraq and from there into Sumerian cuneiform, it developed into proto-Elamite in Iran (and from there into Elamite). We don’t hear much about Elamite because the Elamites weren’t around for a hugely long time, and they have been quiet for a very very long time.
Like proto-cuneiform, what we know of proto-Elamite is from clay tablets that appear to have had things pressed into them. Some glyphs seemed to be made using reeds (like the one adorning this posting), and others appeared to be made using small round things that were pressed into the clay.
The fact that there were two proto-writing systems that experts can tell apart suggests that writing might not be that unusual an invention. Or, perhaps the jump from no symbols at all to protowriting was more important than the jump from proto-writing to writing.
Proto-Elamite is undeciphered, but appears to mostly have been accounting records (like Sumerian).
It is less linear than its direct successor, Linear Elamite, in both how the glyphs are shaped and in how they are laid out. Not only do some of the marks look like they were made with round things (not linear things), but they aren’t really laid out in a line like English text. Sometimes they are, but sometimes they are laid out in a line of boxes, where each box has a glyph made out of lines (like the above glyph) and some pressed-round-thing-shapes. If you think of the nature of receipts and financial record-keeping, this makes sense: you might have a box for “3 goats” and another box for “6 skins of beer”. The goats and beer don’t really have an order to them. This is very different from a sentence of “the three goats drank six skins of beer”, where the sequence of the goats and beer is important, so you don’t have the beer drinking the goats.