Welcome to pests that can be a bigger PITA than Xenia or GSP. I started with one and peaked at 14 after giving some away and a few not making it through an upgrade I'm finally holding at 8. The problem now is that I used dry pukani rock as my base in the upgrade and it has so many nooks, holes, and what not it is impossible to remove them.
The best option honestly that doesn't stress out the whole tank is to aim a power head at it. As already noted do not go 100% full blast but a steady, constant, flow will annoy it enough to move. If after a day it isn't moving increase it a bit. You want it firmly in place but enough action and flow to pick up the base of it and move it. If that makes sense.
Also the light does work. You can place a rock above it or otherwise around it blocking it. It will get upset and move. Those really are your only options. Credit cards work if it is on the glass or round smooth rock. Ice will melt and won't last long eough. Your option is really limited to rock removal to carefully break around it, flow, and lighting. Anything else when that far into a rock is going to stress the tank, you, and the darn nem sadly.