I suspect they are early. Harris period and perhaps for a small period of time afterwards, I'm not really sure.
The bits of seaweed I've seen that are slightly "ropey" (not so well executed - remembering random is not easy to get looking good unless the maker does have innate artistic talent) are all with clear glass, I haven't ever seen a "not-wonderful" amethyst one.
I have no artistic talent, I can't get random squiggly bits I make (with anything), looking good, ever.
I can't even draw a smiley face that looks anything other than downright sinister.
