Salp! The mysterious chained marine organism invading BI waters.
Block Island Maritime Institute — Wondering what those clear, jelly-bean looking "things" are all over the Great Salt Pond? Those mysterious animals you see in strands are Salp. Salp are planktonic tunicates, which float in the water column eating phytoplankton. They can live alone, or in colonies, like the strands you see. They have siphons in which they pull in water, feed, then push the water out. The Salps (or Salpa) end up on beaches where they look like clear, gelatinous potatoes. They are harmless, just sort of a nuisance right now.
This is a great short video about Salp.