3 years ago, around Christmas time ("wow, how original" I hear you say), your mother commissioned one of the human's top sculptors to sculpt her two statues. The first one, the one that most people talk about, is the one that we're looking at. The other is in the background.
Construction started December 3rd and started out in three phases. The first was to actually take the rocks from Jerusalem and put them on the island. That took about a week. The next phase was to build the base. This phase took a while because none of the sculptors were set on the same design, but the outcome is quite a cool thing. The chalice itself is nearly the same as the holy grail, and its face depicts the story of the Deltarune.
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Alright, I'll tell you this universe's deltarune.
Long ago, 6 humans, with the help from monsters alike, came together, and formed an early version of the earth. But, as it so turned out, they forgot one important part about their formation, and so their planet eventually was forced to turn into a great ball of light. Desperate, the humans forfeit their lives so that future peoples could live in a society where they weren't shunned for being friends with each other, and so, they pulled a reboot, which allowed 6 other humans to carry the torch and form our earth.
That's what the two upwards triangles are, the two groups of 6 humans that created our earth. And the downward triangle is our earth. The last "angle" at the top is the vow the humans made to the monsters to rule the earth together. That's why this is so prominent in monster society, it literally represents a broken promise waiting to be rectified.
Now, the base took about 3 days to fully hash out. The final part took the longest. Actually chiseling the statue. This took all the way till Christmas. And days consisted of Alphys and some random actress who dressed up as the Virgin mary having oral sex while in the depicted pose. Needless to say, she and the actress are best friends today. Unfortunately, during the posing, Alphys was paid a visit from aunt flow...
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have I left that image in your brain long enough? Good, let's keep it there for the meantime. The joseph statue was constructed entirely in the last 5 days of the sculpting timeline. It was small, the main statue was big.