- tagmosis
- Tail
- tail fin
- tail segment
- Tangential meshes
- Tangential tubes
- Taphocoenosis
- Teeth
- Teleoconch
- Telokinetal
- Telson
- temperature
- Tentacle
- Tentacle field
- Tentacle marginal
- Tentacles
- Tentaculae
- tentacular cirri
- Tentacular cirrus
- Tentacular club
- Tentacular marginal bulb
- tentacular membrane
- Tentacular pocket
- Tentacular radius
- Tentacular roots
- Tentacular segment
- Tentaculiform structure
- tentilla
- Tergal style
- tergite
- Terminal appendage
- Terminal stage
- Terminal teeth
- Test
- testis
- Tetraradiate symmetry
- Thanatocoenosis
- Theca
- Thecata
- Third shell
- thoracic membrane
- Thorax
- thrust block
- Toxicyst
- Trabeculae
- Tragus
- translucent
- transverse
- transverse commissures
- transverse muscles
- Trichocyst
- tricuspoid
- Tripod
- trochophore
- Trochospiral
- trophozooid
- truncate
- trunk
- tubercle
- Tubercles