Ok so on Monday I wondered what had caused my mystery substrate mound. Many ideas and suggestions given Thanks so I stayed up late on Monday and briefly got a glimpse of what I thought was a pincer but unable to ID. Anyway stayed up last night for an hour and ............ nothing, not a jot, no movement around the rock where the substrate push came from then I come down this morning and more movement but this time it's a TUNNELL :w00t: This is at the opposite side of the rock to where Monday's substrate push came from. The rock is approx 6-8 inches accross. I can't move the rock as it supports the left side of my rockwork. This is slightly worrying if I have something burrowing under it. The hole is about the circumference of a smartie tube and having shined a light into it appears to disappear under the rock. I can see in about an inch or so. Latest pics below.... Monday morning and first substrate movement.. Wednesday Morning and this tunnel appears.. Just disappears under the rock to the left.. Any more ideas with tunnels or how to entice it out and see if it's nice or evil ?