The Great Snail Escape?

[RandomUser7]

I bought some nassarius snails days ago and instead of sifting through the sand for detritus they seem intent on climbing my heater. They've been on my heater for the past few days but today one made the leap to my HOB filter...
It's a new tank but there's leftover shrimp in the sand from previous feedings. Why do they feel more comfortable climbing out instead of in the sandbed where they belong?

 

[blaxsun]

I found that feeding triggers a response with orange-spotted nassarius snails. They emerge from the sand and make a beeline in a fixed direction, often taking them up and over the side of my tank, across the floor, etc.

 

[blaxsun]

(double post)