Storm Studios, the Oslo VFX house behind effects work on The Last of Us, Black Panther: Wakanda Forever and Star Trek: Strange New Worlds, gave a talk at FMX HIVE 2026 called “Call of the Sirens: Percy Jackson S2,” also posted as a SideFX Houdini Talk. It walks through how the studio built the Sirens sequence for Percy Jackson and the Olympians season 2 — and underneath the monster-design headline is a problem I run into constantly from the environment side of the fence: how do you dress a surface that also has to act?
The sirens got ugly on purpose
The Sirens show up in episode 5, “We Check In to C.C.’s Spa & Resort,” which dropped on Disney+ and Hulu on 31 December 2025 as part of the season’s weekly rollout. The show’s writers ditched the “beautiful woman who lures you with song” version of the myth for something closer to the source material’s actual menace: humanoid creatures that read as living rock, embedded in their environment and encrusted with barnacles, starfish and seaweed. Grotesque rather than seductive. It is a good call for a show that has spent two seasons trying to make Greek myth feel dangerous again instead of decorative.
That design choice is also what makes the VFX problem interesting, because “encrusted rock creature” is not one asset. It is an environment surface — the kind of thing you’d normally scatter, dress and forget — that also has to breathe, turn its head and deliver a threat.
Dressing something that moves is a different job
Scattering barnacles, starfish and weed across a static rock is a solved problem. Any environment artist has done some version of it: a scatter system, some slope and cavity masking so the growth clusters in the right places, a pass of hand-placed hero pieces where the camera lingers. It looks right because a rock does not need permission from anything else in the shot. It just sits there.
A performing creature does need that permission, from itself. The moment the Siren’s torso twists or its head turns to track a character, every barnacle riding that surface has to move with it — correct orientation to the new surface normal, no sliding across the skin, no popping as deformation folds geometry in on itself around a joint. Storm’s stated approach was building custom solvers to attach the barnacles procedurally, which is the right instinct: you do not want an animator or a look-dev artist hand-placing thousands of encrustations across every keyframe of a hero creature. You want a system that reads the deforming surface and keeps the dressing glued to it, shot after shot, revision after revision, without anyone re-touching it by hand.
I have solved smaller versions of this same problem — geometry scattered across a mesh that then gets deformed — and the failure mode is always the same one: the dressing looks great on the T-pose and falls apart the second the surface actually does something. A solver built for this has to survive motion, not just survive a screenshot.
The part that’s easy to miss: the performance has to survive the solver
The talk’s other headline term is animation-guided simulation — sims that ride on top of the keyframed or captured performance rather than replacing it, specifically so the creature keeps its “lively, mythical presence” instead of going stiff under a layer of secondary effects. That phrase is doing a lot of work. Any time you bolt a simulation onto a performance — cloth, muscle, jiggle, in this case an entire crust of rock and shell — you risk the sim reading as the dominant layer and the acting underneath disappearing. The eye stops watching the actor’s timing and starts watching the wobble.
Keeping barnacles procedurally stuck to a moving body is only half the problem Storm was solving. The other half was making sure that solving it didn’t cost them the performance they built it on top of. Storm has also talked about procedural workflows letting them iterate fast from design to final shots — which matters more on a sequence like this than on a hero creature you lock early, because a design this unusual almost certainly went through several passes before “grotesque rock woman” read as scary instead of silly on screen.
Worth remembering it’s not one studio’s show
Season 2’s Sirens sequence is Storm’s, but the season’s VFX credits also list ILM, Important Looking Pirates and Raynault VFX, the last of whom reportedly delivered something close to 250 shots of digital environments, set extensions and magical effects elsewhere in the run. A Disney+ fantasy show aimed at a young-adult audience is routinely running a four-studio pipeline now, each vendor solving a different piece of the same mythology. The barnacle solver is a small, specific piece of that — but it’s the kind of small, specific piece that decides whether a monster reads as built or as grown.
Sourced from Storm Studios’ “Call of the Sirens: Percy Jackson S2” talk at FMX HIVE 2026, cross-posted as a SideFX Houdini Talk, plus season 2 VFX credit reporting from The Art of VFX. The cover art on this page is an original graphic made for this piece, not a production still.