Membrane Bubble

A block that generates on the surface of the outer end isles — step on it to get launched.

Launch

Stepping on an active Membrane Bubble launches you upward at membraneBubbleLaunchVelocity (2.0 by default — roughly 40 blocks high), angled slightly by the direction you're looking. See Configuration.

While airborne you get a temporary elytra-style glide: no fall damage, and you'll glide rather than plummet, until you land.

Item entities

If an item entity carrying something "projectile-like" (an egg, snowball, ender pearl, XP bottle, potion, arrow, trident, firework, etc.) lands on a bubble, it gets launched as that item's thrown projectile form instead of just flying upward.

Cooldown

After launching something, the bubble collapses (shorter hitbox, won't relaunch) for membraneBubbleCooldown ticks (60 by default — 3 seconds), then pops back up.