[necovek]

Aren't there significant differences in allowed depth (from minimum of 2m to maximum of 3m)?

[bch]

Good catch. We've run into a problem somewhere along this journey of comparing the compression strength of a snails tooth to the tensile strength of a spiders web.

[necovek]

So a snail's tooth can only hold a 2m deep worth of Olympic pool (sea)water, but it breaks before you get to a 3m deep pool.