Free tool

LEGO Missing Piece Checker

Rule out the usual hiding places first. If the piece really is gone, check the set piece by piece and leave with the element ID LEGO asks for, or a link to buy the part.

Mosasaurus

Checking

6721 Mosasaurus

27 pieces in 19 part and color combinations.

LEGO counts 26 pieces. This inventory comes from a separate parts catalog and lists 27; the two do not always count the same elements, so their totals differ. Spare parts are counted in neither figure.

Before you call it missing

Builders who report a missing piece often find it in one of these places. Tick each one off as you look.

Show

Piece checklist

Animal / Creature Body Parts 24 pieces

  • Animal Body Part, Dinosaur, Back Sail 8 x 2 x 5 Dark Gray Part 40385 Element 4153771 ×1
  • Animal Body Part, Dinosaur Body Quarter with Pin Holes, Dark Gray/Sand Blue/Dark Blue/Red Print Light Gray Part 40373pr0003 Element 4153893 ×2
  • Animal Body Part, Dinosaur Body Quarter with Pin Holes, Dark Gray/Sand Blue/Dark Blue/Red Print Light Gray Part 40374pr0003 Element 4153897 ×2
  • Animal Body Part, Dinosaur, Head Toothed, Jaw Bottom Light Gray Part 40388 Element 4152987 ×1
  • Animal Body Part, Alligator / Crocodile / Dragon Upper Jaw / Dinosaur Tongue Red Part 6027 Element 4152991 ×1
  • Animal / Creature Body Part, Dinosaur / Dragon Arm, Left Sand Blue Part 6128 Element 4152994 ×1
  • Animal / Creature Body Part, Dinosaur / Dragon Arm, Right Sand Blue Part 6127 Element 4152992 ×1
  • Animal / Creature Body Part, Dinosaur / Dragon, Foot Sand Blue Part 40393 Element 4154171 ×2
  • Animal / Creature Body Part, Dinosaur Neck / Tail Ring Sand Blue Part 40375 Element 4152934 ×2
  • Animal / Creature Body Part, Neck / Tail, S Curve with Pin Sand Blue Part 40396 Element 4153769 ×1
  • Animal / Creature Body Part, Tail / Neck, Base Section with Black Pin Sand Blue Part 40395 Element 4152998 ×1
  • Animal Body Part / Plant, Tail / Claw / Horn / Branch / Tentacle, End Section Sand Blue Part 40379 Element 4174997 or 4152978 ×1
  • Animal Body Part / Plant, Tail / Neck / Branch / Trunk, Middle Section with Pin, Round Pin Hole Sand Blue Part 40378 Element 4152976 ×1
  • Animal Body Part, Dinosaur / Whale Flipper with Pin Sand Blue Part 40386 Element 4154749 2 spares in the box ×4
  • Animal Body Part, Dinosaur, Head, Small Sand Blue Part 40384 Element 4175028 or 4152981 ×1
  • Animal Body Part, Dinosaur, Legs Short, Dark Gray, Red, Blue Print Sand Blue Part 40380c01pr0003 Element 4153000 ×1
  • Animal Body Part, Dinosaur, Mosasaurus Head, Toothed with Pin, Dark Gray, Red, and Dark Blue Print Sand Blue Part 40387pr0001 Element 4153921 ×1

Bricks Sloped 2 pieces

  • Brick Sloped 45° 2 x 2 Dark Gray Part 3039 Element 4109984 ×2

Containers 1 piece

  • Packaging Lid, Canister Top, Dinosaurs Black Part 41342 ×1

Tick each piece as you find it, or mark it missing.

When a piece really is missing

Ask LEGO

LEGO takes requests for pieces missing from a new set through its customer service site. The form asks for the set number and each piece's element ID, the number printed beside the piece in the parts list at the back of the instructions. This checker lists both.

Request a replacement from LEGO

Buy the piece

Mark a piece missing and your list links it to an eBay search for that part, which also covers pieces from older or second-hand sets.

Keep a record

Copy or download your missing list (the CSV opens in any spreadsheet), or print the whole checklist and tick pieces off on paper. Your marks stay in this browser, so you can check a big set over several sittings.