Sorry, I have to disagree with Eric. One tank higher than the other CAN cause overflows. 2 tanks at the same height (which is what you want to set up, just with different names) linked with a siphon type tube can NOT overflow. As long as the pump is not too powerful (which you wouldn't want...
A siphon and one pump is way safer than trying to match 2 pumps. Failure of either pump gives you a flood.
One pump and 2 siphons is pretty bulletproof as long as each siphon can handle the same volume as the pump can push.
2 and 3 look like Hair worms, no feeding tentacles but quite long gills along the body. Good detritus feeders which burrow in the sand and under rocks.
My pleasure :-) and yours too I think. I have one with plain colour tentacles but no good photo of it. I should add that anything which clicks is not a Mantis or bad. I have a couple of Pistol shrimp which click too and are good fun (as long as your rocks are firmly based because they are...
I took this photo of my Spaghetti which has banded tentacles up to 6inches long. It started off in the coral rubble base but now lives in a rock half way up the tank.
I'm pretty confident I have good coloured Spaghetti worm here, and a Hair worm which came out for a walk. Never seen that before! Got a mean crab now too, but that one has to go (trap set).
:flame:
I'm no expert, but I have a chiton and a limpet and it looks somewhere between those. If it is, it's an algae eater and I regard them as good if slow cleaners.
I'm sure there'll be a real expert along soon :-)
Just to open the horizon, I got round door/stair issues with a big open steel frame mahogany tread spiral stair. Looks great, does the job and incredibly easy to carry unbelievably big stuff up too.
Good luck. Great posts and projects :-)