4 ideas
An organism builds successive sealed chambers, occupying only the newest while abandoning but retaining all prior ones for buoyancy. Growth is not replacement but accumulation: the abandoned past structurally supports the living present rather than being discarded.
A shell's logarithmic spiral is not designed but emerges from a constant-ratio growth rule applied iteratively over time. Viewing biological shapes as the visible trace of a simple recursive equation lets you predict form from rule rather than cataloguing each appearance separately.
A lineage that persists nearly unchanged for hundreds of millions of years shows that long-term survival can come from stability in a deep, stable niche rather than continual adaptive innovation. Evolutionary success measured by duration favors conservatism, undercutting the assumption that change is always advantageous.
Vertical position is managed by adjusting gas and fluid ratios across multiple sealed compartments rather than by continuous muscular effort. Distributing a control problem across many independently tunable units allows precise positioning with minimal ongoing energy expenditure.