Smooth edges no harm to animals and plants, you can rest assured that using. NB the glass pebbles are 0.93LB Heavy Enough BUT SMALL BAG! Product Size: Each clear pebbles about 6 to 9mm/0.24-0.35". For example, if your tank size is 6.3 6.3", it will needed 1 bags for about 0.4” of depth.
eBay