凸線

Tommy Turtle (tu) is installing a convex (凸) lens to the outer hull of the space station (Ø1). The lens is so convex that Tommy Turtle is unable to embrace it with his arms.

线 = 戋 + 纟 : Mnemonic symbol: barbed wire.

线 = 戋 + 纟 : The silk worm wants to use the floating tank in the anthill's bathroom, but there's already Marie Curie inside—and she secured the tank by setting up barbed wire all around it.