The 329 is a barretter or current stabiliser for use on heater chains to reduce the switch-on surge and consequent damage to heaters.
This barretter has three pins and a centre tapped filament.
The dome carries the Philips name and the Type designation. The other word is industrial and with a current rating unlike any valve heater ratings this was probably designed for a different current stabilising application.
A clear view of the three and the two. The nine requires a glass to see as it is very faint.
The filament wire held in the supports attached to the central glass rod. The wire is probably iron and the envelope probably has a hydrogen gas filling.
The wide glass tube envelope is 31 mm in diameter, and excluding the B9A base pins is 100 mm tall.