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Moldbygg (/ˈmoʊldˌbɪg/) is an enemy the protagonist encounters in Waterfall. It is an advanced form of Moldsmal. However, it does not appear in Hard Mode, which instead features Moldessa.



It pretends to be a Moldsmal, but once approached or attacked, it reveals itself as Moldbygg. It can be identified before it transforms, as it is completely stationary and lacks animation in its Moldsmal form. Additionally, it cannot be spared immediately, unlike Moldsmal.

In Battle

Appears With


  • Small Moldbyggs sprout from the bottom of the screen, shooting bullets at the protagonist's SOUL.
  • A reverse of Moldsmal's attack:
    • Eight bullets appear from the edges of the screen, converge on a point, then rise.


  • Unhugging Moldbygg makes it spareable.
  • If Hug is used against Moldbygg, the SOUL's SPEED decreases for the battle. Touching Woshua afterward causes the latter to run away.


  • ... [Neutral]
  • Roar. [Neutral]
  • *Chaste wiggle* [Neutral]
  • Guoooh! [Neutral]
  • *Slime sounds* [Neutral]

Flavor Text


  • Moldsmal is very normal. [Neutral]
  • Moldsmal is having quiet time. [Neutral]
  • Moldsmal sits motionless. [Neutral]
  • Smells like a bait shop. [Neutral]
  • It's a slime mold...? [Check]
  • You lie immobile with Moldsmal. Suddenly...! [Imitate]
  • You wiggle your hips. Suddenly...! [Flirt]


  • One size greater than Moldaverage. [Check]
  • Moldbygg and Woshua appear. [Encounter with Woshua]
  • Moldbygg gyrates reservedly. [Neutral]
  • Smells like a bait shop. [Neutral]
  • Moldbygg mills about in the corner. [Neutral]
  • Moldbygg needs some distance. [Neutral]
  • You lie down. Moldbygg lies down too. Moldbygg understands life now. [Lie Down]
  • You hug Moldbygg. Gross slime covers you. Your SPEED decreased. [Hug]
  • You don't hug Moldbygg. It appreciates your respect of its boundaries. [Unhug]
  • Moldbygg seems comfortable with your presence. [When spare conditions are met]
  • Moldbygg has seen better days. [Low HP]


  • Moldbygg does not make an appearance in New Home to tell the story of Asriel Dreemurr.
  • The "bygg" of "Moldbygg" is a pun on "big," as it is pronounced "mold-big" and is larger than Moldsmal (a pun on "small").
    • Its Check description mentions a "Moldaverage" (a pun on "average"), but no such monster is encountered in game.
  • Moldbygg is one of the monster species making up the Amalgamate named Lemon Bread; specifically, Lemon Bread is spared by un-hugging, an ACT adopted specifically from Moldbygg, and Lemon Bread appears to have Moldbygg's top-most tier segments as her teeth and several bumps from Moldbygg's lower tiers.
    • This is further illustrated in Lemon Bread's idle animation as she performs a "roaring" action, which might be a reference to one of Moldbygg's quotes.