I’m not quite getting it. These tubes interlocked to do what? Build a stay-in-place form for a masonry arch?
Maybe. The varying thickness of the ornamentation on these objects are consistent with a Crinoid stem, a marine animal attached to a solid substrate, or object.
Were they pure calcite, and round on the end view?
Look for them in in the literature as calcite jewelry: necklaces,, bracelets, ear-rings, etc.
We just glossed over that at culinary school, so I'm not completely clear on it myself.
Fictile tubes (or vaulting tubes) are architectural elements that sustain and underline the shapes of cupolas and vaults. Several of these, sampled in three churches of Milan (S. Ambrogio, S. Lorenzo and Duomo) have been recently dated at the Archaeometry Laboratory of Milano Bicocca University. These architectural elements, differently shaped, styled and sampled from different structures, were all produced, according to thermoluminescence (TL), in the period 9701080 AD.
Or, to sharpen the post...... what is a vaulting tube?