[lepton]

It looks like a giant ball of string.

It looks like a spherical metal tank (helium or fuel component) covered with insulation that has frayed badly.

[XBob]

It looks like a spherical metal tank (helium or fuel component) covered with insulation that has frayed badly.

not exactly = that is the tank structure, not insulation. tanks are not metal, they are made of wrapping composite, tape, which I think is to be fiberglass, into a sphere, making a tough, light tank.