Ocean
StarNinjas

Adds coral reefs, fish, decorative ocean blocks and much more!

Loria (alpha)
siegment

Survival in hardcore acid-alien sci-fi themed world

Poly Decor
PolySaken

My spin on decorative stuff.

Plastic Box
Starbeamrainbowlabs

Adds a recolourable plastic box. Fork of @cheapie's version with improvements.

Bridges and stairs, factory-style
narrnika

Adds a steel bridges, railings and stairs in Minetest.