rubble
 

Okay Im setting up my 60gal acrylic mantis shrimp tank but Im pretty much broke (yay for university student life). The only thing I need now is rubble. I know I can use shells and rubble of dead or live rock, but can I just use rocks/pebbles I'd find on the ground (ie free!)? Should I worry about bad stuff like toxins/silicates getting in my tank?

I apologize if this is a noob question.

id do it,
just make sure they are very clean.

lol an old has been dug up! in the end i just took a larger piece of LR and smashed it up... it at least is porous unlike pebbles. plus when a mantis uses rubble to make a home it needs irrregular pieces to fit together and i dont think smooth round pebbles would serve very well.