Phytolith mystery!

One of the nicest things about my job is hearing about the successes of past students. It makes me genuinely happy to see students with enthusiasm and passion for environmental archaeology go on to build successful careers. I taught my first postgraduate students during my time at Edinburgh back in  2013, and they are all doing so well. One recently finished a PhD and gained a great postdoctoral position, another is on track to finish their PhD very soon and has recently published their first paper, and another has a fantastic job as a research technician in a top environmental archaeology lab. I had an email from the latter recently regarding the identification of some unknown phytoliths. They appear to be generic grass long cells, but have odd striations that I have never seen before. The striations are all in the same direction - could this be an artefact of processing or is it surface decoration? I am not sure about surface decoration, it looks a bit too regular. has anyone seen anything like this before? They are from a Bronze Age site in the Levant.