The average size of P pansa has halved in the last thirty years - from 60mm to 30mm long. Before 1980, some snails grew to more than 100mm.

The snail lays egg capsules, which hatch into planktotrophic larvae - meaning they feed on plankton. The larvae can delay settlement for 6 months or more.

The snails can live for about 11 years.

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