To the Bone Room!

Depicted moment
Carver summons Pearl into the Bone Chambers. The grave elemental meets the surviving bone beast amid a floor completely buried beneath the dead while Rage, Carver, and Ignatius close in around them. The session ends before the larger creature falls.
Artistic interpretation
The bone beast’s exact anatomy, club, and the ossuary’s architecture are interpretive because the party has not identified the creature. Pearl’s height is shown at roughly nine to ten feet—larger than the adventurers but distinctly smaller than the bone beast. The density of loose bones reflects the chamber’s overwhelming mass of remains.
Canonical status
Accepted Session 16 cover artwork and canonical visual reference for Pearl’s summoned form: a bipedal body of compacted grave earth, roots, stones, bones, broken gravestones, and coffin remnants.
Alt text
In a ruined gothic chamber, countless skulls, ribs, and long bones completely cover the floor. Pearl, a nine-foot grave elemental formed from dark earth, roots, gravestones, coffin boards, and embedded bones, crouches opposite a much taller humanoid beast constructed from fused skeletons and raising one enormous bone club. Rage advances with a single greataxe, Carver faces the clash in his pointed hat and goggles, and the black dragonborn monk Ignatius braces to strike.