I'm a bit embarrassed to ask about this - this is in my first tank and iirc it was a 1 2 Grow and I'm sure it's common and easy. I have trawled around image searches and looked at the database and I can't see it. It's the only thing I haven't written down! It grows like mad and I can just snip bits off and shove it in the substrate and it takes off again. Thanks in advance.