Octonauts· Season 3 · Episode 18The Urchin InvasionS03E18·March 21, 2014·11m·CBeebiesThe Octonauts head to the kelp forest to visit Shellington's sister, Pearl, and her newborn son Periwinkle - only to find the forest endangered by an infestation of kelp-eating urchins!Streaming on (US) See allSharePreviousThe Immortal JellyfishS03E17NextThe Hammerhead SharksS03E19Keep goingSeasonSeason 3 ranked & reviewedEvery episode in airing order with ratings and dates.StreamWhere to watch OctonautsEvery streaming service and region, checked around the clock.MatchupShows like OctonautsThe closest matches, ranked by overlap and rating.
