The Artifact Collection/Mothership Day (S01E18)

S01E01 The Plushie Collection/The Bouncy Ball Collection S01E02 The Fake Mustache Collection/The Lint Dinosaur Collection S01E03 Lemons!/The Butterfly Collection S01E04 Whole Lotta Lotta/Leaf it to Carl S01E05 The Tool Collection/The Stick Collection S01E06 The Fall/The Word Collection S01E07 The Remote Control Collection/The Super Blue Moon Sleepover S01E08 A Forrest of Plans/The Marble Collection S01E09 The Magic Trick Collection/Listen Coach S01E10 The Sticker Collection/The Baby Stuff Collection S01E11 The Puffball Collection/The Bottle Cap Collection S01E12 A Wiggle Waggle Worries/The Pine Cone Collection S01E13 The Autograph Collection/the Rope Collection S01E14 A Collection to Get Rid Of; The Button Collection S01E15 Rhythm Blues/Giving Up the Ship S01E16 Twin Sister Hamster Sitters Incorporated/The Sneaker Collection S01E17 The Gratitude Collection/The Pet Rock Collection S01E18 The Artifact Collection/Mothership Day S01E19 The Lost Yo-Yo/Rainy Day S01E20 A New Friend/Lotta the Copycat S01E21 The Potato Collection/Nico and the Nutty Buddies S01E22 The Green Piece/The Fuzzyworld Book of Records S01E23 A Fuzzytown Halloween