odd hitchhiker - ID please?

[c_scherer123]

I got a new 1lb peice of liverock and gave it a 15min freshwater bath, using the turkey baster to blast holes and remove well over a dozen bristleworms. I also discovered scuds and corepods and put those in the tank.
I put the rock in a small plastic container (barely big enough to hold it - it is still in the container) to ensure there were no aipista - but last night I turned the room light on and saw 2 odd hitchhikers - neither I can seem to identify... Both hid very fast with the presence of light (sorry no pictures - I will try tonight).

One was a "rocket worm" - like a 5mm microworm rocketing through the water at a speed that put my FW danios to shame - crawling over the rock like a centiped, but far faster. I am sure it is harmless. No chance for a picture - that thing is just way too fast...

The second... How to describe it? It never did entirely leave the hole it was inhabiting, the part that reached out looked kind of like a snails siphon. It stuck out about 2", it was brown with black splotches. Very light sensitive, I had to turn the lights on a 1/2 hour later to make sure I actually saw something because it hid so fast. This one has me confused...

Any ideas? I am new to saltwater, so these things could be common as algae and still be a mystery to me...