Where do hitchhikers and critters come from?

[mpjmeyer]

I'm assuming they come from rock that gets added to the tank but I'm always reading stories here about members trying to ID living creatures that suddenly appear in the tank that weren't there before. I'm not sure if I'll get any hitchhikers since my rock is dry live rock from BRS but I could def. be wrong. What other sources could they possibly come from?

 

[donnievaz]

Frags and plugs is one source, cheato or other macroalgae. Basically anytime you put anything in your tank that's been in the ocean or someone else's tank there's the potential of introducing a hitchhiker.

 

[Reef man 89]

I started with dry rock from BRS to and end up getting GHA and Hydroids from the frags I picked up.