Or search: shell, cutis, scute, mantle, shield, turtle, mollusk, stratum, mollusc, pallium, corneum, carapace, cuticula, epidermis, shellfish
3 Syllables: SUU
beautiful, crucible, cubical, funeral, Juvenal, juvenile, movable, moveable, musical, mutable, numeral, suitable, tubercle, usable, usual
4 Syllables: USUU
deducible, excusable, immovable, immoveable, immutable, inscrutable, reducible, removable, renewable, unsuitable
5 Syllables: UUSUU
constitutional, indisputable, inexcusable, institutional, irreducible, irrefutable, longitudinal, pharmaceutical
6 Syllables: UUUSUU
unconstitutional

Found 34 words across 4 groupings. Skipped 2 excess words of a similar stem.