| Pachymatisma johnstonia | |
|---|---|
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Porifera |
| Class: | Demospongiae |
| Order: | Tetractinellida |
| Family: | Geodiidae |
| Genus: | Pachymatisma |
| Species: | P. johnstonia |
| Binomial name | |
| Pachymatisma johnstonia | |
| Synonyms | |
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Pachymatisma johnstonia is a species of sponge belonging to the family Geodiidae. A species of the north-eastern Atlantic coasts, this is a usually grey encrusting sponge with large prominent oscula and a pale yellow interior. The size and form depends largely on the extent of its exposure to waves. In heavily wave-exposed locations, it is usually small and thin but in more sheltered places can grow to over 50 cm across and 15 cm thick.
