Alex Mustard / A diver exploring a coral reef with formation of brown tube sponges (Agelas conifera) red rope sponges (Amphimedon compressa) and deepwater sea fans (Iciligorgia nodulifera) East End, Grand Cayman, Ca...

Juergen Freund / Brown tube sponge (Agelas tubulata) in the reef, North Sulawesi, Indonesia.

Alex Mustard / Colourful coral reef wall, with yellow branching tube sponges (Pseudoceratina crassa), brown tube sponges (Agelas conifera) and red rope sponges (Amphimedon compressa), in front of deepwater sea fans...

Georgette Douwma / Graysby fish (Cephalopholis cruentatus) lying on Brown tube sponge (Agelas conifera) Bonaire, Netherlands Antilles, Caribbean

Georgette Douwma / Brown tube sponge (Agelas conifera) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Brown tube sponge (Agelas conifera) and Row pore rope sponge (Aplysina cauliformis) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Brown tube sponge (Agelas conifera) and Row pore rope sponge (Aplysina cauliformis) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Brown tube sponge (Agelas conifera) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Brown tube sponge (Agelas conifera) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Pete Oxford / Brown Tube Sponge (Agelas conifera), Bonaire, Netherlands Antilles, Caribbean

Juergen Freund / Brown tube sponge {Agelas wiedenmayeri} Caribbean