The 'coffin lid' or 'top half of the pecan shell', or however you'd like to interpret the odd meteor called 'Fëa' is only a fraction of the total weight of the thing. Although Celsior is not the strongest Prince in the kingdom, at his maximum effort the top clicks off and falls to the powdery cavern floor with a thud.
With it completely removed, the dead crystals completely exposed, the smell of rot and decay is nearly unbearable.
~Foul!~
Another chocolate cake starts to make its way up Greelob's magical cornucopia of a throat, but he chortles it back down quickly.
A stinking cloud has been unleashed, assaulting not only your wide open nostrils, but the pores on your skin with its alien death stench. Celsior, Lou and Opal need Con saves against a DC 13 or vomit and retch (consuming your Action). Lazuli and Yahs can make the save with advantage because of plasmoid resistance to poison.
Each half is about 250 lbs, so Celsior can manage with his Push/Drag/Lift of 280.