Official LEGO® image · © LEGO Group and/or the respective rights holders. Source: LEGO Italy ↗

Classic · SET 10404

Ocean's Bottom

A creative box with a castle, creatures and marine ideas.

Pieces: 579
Release year: 2018
Theme: Classic
Set number: 10404
LEGO recommended age: 5+
Archived regional retail price · Germany: 29.99 €

Official LEGO archive Official building instructions

Archived regional retail price in the stated market and currency. It does not establish the Italian launch price; no estimated currency conversion. Brickset ↗ · Reference checked on 22 October 2026

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Official English name verified at: LEGO English archive ↗ · Checked on 26 October 2026.

TIME TO BUILD

How long does it take to build Ocean's Bottom?

First build · with help if needed

For younger children, we estimate the first illustrated setup, with adult guidance when needed. Ranges reflect building familiarity, not a child’s age or ability. Free play and learning have no completion time.

Editorial estimate · first setup

Beginner

≈ 45 minSuggested range27 min – 1 h 12 min

Intermediate

≈ 30 minSuggested range18 min – 48 min

Experienced

≈ 21 minSuggested range12 min – 34 min

First guided arrangement: one model for 3 in 1 sets, a small composition for creative boxes, and setup alone for expansions. Excludes play, breaks and electronic configuration. These are broad editorial estimates, not measured times or targets to meet.

How we estimate times · sources and method

Editorial assessment: A creative box with a castle, creatures and marine ideas. The time covers one first illustrated build rather than every combination in the box. Creative boxes and modular decorations refer to one first illustrated arrangement; 3 in 1 sets to the main model only, and expansions to their first setup. An adult may guide the child. Ranges reflect building familiarity, not age or development; they do not measure play, learning or a speed contest. For older sets, unnumbered bags or previously mixed pieces may prolong sorting. No verified timed build: indicative values with substantial variation.

Sources do not always specify the builder’s experience. The three experience bands are our editorial assessment, based on the complexity of the set and individual accounts where available.

LEGO · set-specific instructions ↗
Official name, pieces, age and imagery; no timed building data.
LEGO · set manual ↗
Document for this set number. The duration is an editorial estimate, not a LEGO timing.

Checked: 26 October 2026 · Method v1.0 · Limited reports; not a statistical average.

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Build your own story.

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MAKE ROOM FOR YOUR NEXT BUILD

How much display space does it need?

Assembled-model dimensions are not yet documented for this set. Box dimensions cannot tell you how much display space it needs.

BEYOND THE BRICKS

Did you know?

The model, the history, the ideas

Inside the set

Many subjects

A castle, dragon and vehicles show the variety of suggested ideas.

LEGO source

First setup

The time covers one first illustrated build rather than every combination in the box.

LEGO source

Beyond the set

The stories, places and inventions behind your build.

Coral is an animal

Many corals are colonies of small polyps that build a calcium-carbonate skeleton. Their branching appearance can make them look like plants.

Read the full story

Many corals consist of hundreds or thousands of polyps capturing food with tentacles. In hard corals, calcium-carbonate skeletons accumulate across generations and build reef foundations. Branching shape and immobility may suggest a plant, but not the way an individual polyp feeds.

NOAA

An alliance within the tissues

Many corals host microscopic algae that use light for photosynthesis. This partnership supports reef growth; expelling the algae can lead to bleaching.

Read the full story

Many corals shelter microscopic algae within their tissues. Protected algae use coral waste products, while photosynthesis supplies substances useful to the animal. Disruption can cause bleaching. A bleached coral is not automatically dead, but is stressed and faces increased mortality.

NOAA

Expanded stories updated on 29 October 2026

Written by HowLongToBuild · Sources are linked with each story · Checked on 26 October 2026. Historical facts and story details refer to the context described.

THE COMMUNITY’S EXPERIENCE

What was it like to build?

Three separate scores from 1 to 10. For difficulty, 1 means very easy and 10 means very difficult.

No approved ratings yet. Scores are never generated by this site or inferred from the recommended age.

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Building tips from the community

Specific steps, useful checks and sticking points. Contributions appear after moderation, in their original language. Do not upload instruction pages or personal contact details.

No approved tips yet.

SET THE MOOD

A soundtrack for your build

· Selected for the subject and atmosphere

Ponyo’s musical storytelling accompanies water, small journeys and wonder. This pairing follows the model’s aquatic subject, with more understated alternatives for a build with fewer changes of scene.

OUR PICK

Ponyo on the Cliff by the Sea (Original Soundtrack)

Joe Hisaishi

Narrative and cinematic

Spotify ↗Apple Music ↗

Your listening moodChoose a different soundtrack

Editorial suggestions, not official soundtracks for the set. External services may require an account or subscription; editions and availability can vary by country. Suggest another soundtrack →

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