My Uro did have a habit of getting the crushed walnut substrate up his nose (disclaimer: crushed walnut substrate should NEVER NEVER NEVER be used, chalk this instance up to poor information and an inexperienced Uro keeper. This occurred 5 years ago). Since he has been on sand he has not seemed to have had a problem with it. Like you though, I always wonder how he doesn't end up with a nose full!
Elizabeth
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1.0 Mali Uro Archimedes
0.0.1 Egyptian Uro Zuberi Mosca Khu (Mosca)
0.0 Fish
0.1 Sulcata Minnie
1.1 Iguanas Flik and Loki
0.1 Newfoundland Jasmine
0.1 Feline Winter
Indiana & Wisconsin