Shape, can be made with small stipes (stalks) of the Nereocystis
"bullwhip" kelp which is common in Washington and British Columbia.
Likely if your light station is a rocky island it is ringed by a
"forest" of bullwhip kelp.
Here is a recipe for sweet kelp pickles that I have found very successful: 2 quarts of hollow Nereocystis bulbs and stipes cut about 1/2" long 2 C sugar or 1 1/2 C honey2 tsp each of celery seed, turmeric, mustard seed, and pickling spice 1 medium onion sliced1 tsp salt1 clove garlic or 1/4 tsp powdered garlic 1 1/2 C white vinegar