Such algae are very easy to knit. you are not to be a very skilled worker. You should have basic crocheting skills.
This crochet pattern is in English (US terms).
You may use any yarn you like and 1- 3 mm hook size). The crochet size depends on your yarn.The thinner your hook and yarn, the smaller and finer the algae will be. Great occasion to use yarn leftovers.
The color of the algae can be almost anything.